Learn Melanoma reviewer workspace

Generated from case-data.js by node scripts/academy-review.js --write. Do not hand-edit. If the cases change, regenerate this file.

Learn Melanoma is a teaching sequence. It does not certify competence, estimate a probability, or act as a diagnostic device. New cases stay review required. Teaching type is a lesson shape, not a diagnosis and not a score.

Primary path: 49 cases. Registry: 51. Teaching 26, reasoning 16, expert-challenge 7. 1. Recognition: 4; 2. Differentiation: 9; 3. Pattern integration: 18; 4. Diagnostic traps: 16; 5. Advanced reasoning: 2.

A primary-path case needs a source, a local image, a differential, a distinct skill assignment, and honest review status. Academy cases also need observation prompts, feature certainty and weight, a closest mimic, and a non-trivial trap or take-home rule. Legacy pilots stay on the path without new clinical fields. This is not a numeric score and not a pass mark.

Verification, not a total

Melanoma labels by stored confirmation method: clinical_diagnosis: case-g18-12, case-g24-01, case-g24-02, case-g26-07; expert_diagnosis: case-g18-10, case-g18-11, case-g21-07; histopathology: case-acral-melanoma-plantar, case-g25-01, case-g25-03, case-g25-04, case-g25-05, case-g26-01, case-g26-03, case-g27-03, case-g27-04; source_dataset_diagnosis: case-g18-01, case-g18-02, case-g18-03, case-g18-04, case-g18-05, case-g18-06, case-g18-07, case-g18-08, case-g18-09. Histopathology-confirmed melanoma: case-acral-melanoma-plantar, case-g25-01, case-g25-03, case-g25-04, case-g25-05, case-g26-01, case-g26-03, case-g27-03, case-g27-04. A larger total does not make the other methods histopathology. Clinical review remains deferred.

Outside the primary path

Field change on the dorsum of the hand (case-ak-field-hand) stays in the library and outside Learn Melanoma. Default reason: it is not a melanoma-pathway skill case.
Two neighboring lesions on the upper back (case-scc-ak-paraspinal) stays in the library and outside Learn Melanoma. Default reason: it is not a melanoma-pathway skill case.

Dark lesion thicker on one side (case-g18-01)

Teaching type: Teaching case
Curriculum level: 1 · melanoma
Skills: Asymmetry, Evidence weighting
Recorded diagnosis: Cutaneous melanoma
Disease record: cutaneous-melanoma
Confirmation: source_dataset_diagnosis — The NCI description says this is asymmetrical melanoma and that the left side is much thicker than the right. The caption does not state histopathology, Breslow thickness, or a histologic subtype. Those items are not added.
Site: Skin, site not named on the source

Provenance

clinical · Public domain · National Cancer Institute

File: assets/media/cases/case-06-clinical.jpg

Source: National Cancer Institute, via Wikimedia Commons

National Cancer Institute. Public domain.

Modification: other-described — Recompressed for web delivery and file metadata removed. No crop and no annotation.

Observations

One dark brown-black lesion on skin.
One side looks thicker than the other side.
A measuring scale runs along the lower edge. No measurement is read off it here.

Observation prompts

Which half of the dark lesion looks thicker?
A measuring scale is in the frame. What does it not let you claim?

Features, certainty, and weight

Clinical morphology, dermoscopic structure, and image context are separate. An image mark does not compete with a diagnostic structure.

Clinical morphology

Asymmetric thickness — Clearly visible; Major clue

A thicker half is a clue. It is not specific for one diagnosis.

Canonical pattern: asymmetric-thickness. Educational role: Diagnostic structure. Case certainty and weight stay on this case.

Dermoscopic structure

None stored on this case.

Case-specific observation

None stored on this case.

Context and image information

Measuring scale without a recorded reading — Clearly visible; Weak

A scale in the frame is not a measurement and not a diagnosis.

Canonical pattern: measuring-scale-in-frame. Educational role: Image mark, not a skin finding. Case certainty and weight stay on this case.

Differential

Cutaneous melanoma

Why it fits: Asymmetric thickness; Dark color

Why not: The photograph does not contain a pathology report

The NCI catalog names melanoma. Level 1 practice is to see the asymmetry before using that name.
Pigmented keratinocyte tumor

Why it fits: A dark raised lesion can be keratinocytic

Why not: The source label is not a keratinocyte tumor

A second possibility stays on the list until the source, and in practice a biopsy, settles it.
Hemorrhage in a benign lesion

Why it fits: Very dark color can be blood

Why not: The source presents this as a melanoma teaching image

Color depth alone does not prove blood.

Closest mimic

Pigmented keratinocyte tumor

A dark raised lesion can be keratinocytic. This clinical frame does not show dermoscopic structures that separate the two, so the catalog sentence is what names it.

Why not

None recorded on this case.

Reasoning

One dark lesion is thicker on one side. The NCI caption calls the lesion melanoma and does not include a histopathology report.

Asymmetric thickness is clearly visible and is the major clue. It is not specific. The diagnosis weight is the NCI sentence. The scale is visible and weak, because no measurement is read from it. There is no histopathology sentence to weigh.

Diagnostic trap

Treating asymmetry as proof, or ignoring it because a ruler is in the frame.

Mentor note

Do not invent a thickness in millimeters. The scale is visible; a number is not recorded here.

Take-home rule

Describe the uneven half first. Keep the source diagnosis separate from the clue.

Management brief

Management is not chosen from this photograph. Concerning pigmented, pink, or nail-unit lesions are assessed in clinic. When melanoma is suspected, histopathology is the usual confirmation. This brief is not a protocol, not a probability, and remains review required.

Dark lesion with an uneven edge (case-g18-02)

Teaching type: Teaching case
Curriculum level: 1 · melanoma
Skills: Border irregularity
Recorded diagnosis: Cutaneous melanoma
Disease record: cutaneous-melanoma
Confirmation: source_dataset_diagnosis — The NCI description says this is melanoma with a border that is uneven, ragged, or notched, as part of an ABCD teaching set. It does not state histopathology.
Site: Skin, site not named on the source

Provenance

clinical · Public domain · National Cancer Institute

File: assets/media/cases/case-07-clinical.jpg

Source: National Cancer Institute, via Wikimedia Commons

National Cancer Institute. Public domain.

Modification: other-described — Recompressed for web delivery and file metadata removed. No crop and no annotation.

Observations

A small dark lesion sits on otherwise even skin.
The outline is notched rather than a smooth oval.
Black and dark red-brown color are both visible. A centimeter scale is at the lower edge.

Observation prompts

Is the outline a smooth oval or notched?
Which dark colors are actually in the lesion?

Features, certainty, and weight

Clinical morphology, dermoscopic structure, and image context are separate. An image mark does not compete with a diagnostic structure.

Clinical morphology

Notched border — Clearly visible; Major clue

A notched edge raises concern and is not specific.

Canonical pattern: notched-border. Educational role: Diagnostic structure. Case certainty and weight stay on this case.
More than one dark color — Clearly visible; Supportive

A second dark color supports concern. It is not specific and it is not a count of colors beyond what you can see.

Canonical pattern: color-variegation. Educational role: Diagnostic structure. Case certainty and weight stay on this case.

Dermoscopic structure

None stored on this case.

Case-specific observation

None stored on this case.

Context and image information

None stored on this case.

Differential

Cutaneous melanoma

Why it fits: Notched border; More than one dark color

Why not: No pathology text is in the caption

The source names melanoma for this border example.
Seborrheic keratosis

Why it fits: A dark stuck-on lesion can have an irregular outline

Why not: The surface here is not a thick waxy plaque in this frame

Border irregularity is shared. Do not stop at the first familiar benign name.
Traumatized nevus

Why it fits: Dark red color can follow trauma

Why not: No trauma history is in the source caption

A history of trauma is not visible in a photograph.

Closest mimic

Seborrheic keratosis

An irregular dark outline is shared with seborrheic keratosis. This frame does not show a thick waxy plate, so that mimic stays possible and is not preferred from pixels alone.

Why not

None recorded on this case.

Reasoning

The lesion has a notched outline and mixed dark colors. The NCI caption calls it melanoma and does not cite histopathology.

The notched border is clearly visible and is the major clue. The second dark color is supportive. Diagnosis weight is the catalog sentence only. No pathology sentence is present.

Diagnostic trap

Using the word notched as if it were a diagnosis.

Mentor note

The scale lets you see that the lesion is small. Small does not cancel an uneven edge.

Take-home rule

An uneven border is described before it is named.

Management brief

Lesion with several dark colors (case-g18-03)

Teaching type: Teaching case
Curriculum level: 1 · melanoma
Skills: Color variegation
Recorded diagnosis: Cutaneous melanoma
Disease record: cutaneous-melanoma
Confirmation: source_dataset_diagnosis — The NCI description says melanoma with coloring of different shades of brown, black, or tan, as part of an ABCD set. It does not state histopathology. A separate Commons file of the same photograph was not added.
Site: Skin, site not named on the source

Provenance

clinical · Public domain · National Cancer Institute

File: assets/media/cases/case-08-clinical.jpg

Source: National Cancer Institute, via Wikimedia Commons

National Cancer Institute. Public domain.

Modification: other-described — Recompressed for web delivery and file metadata removed. No crop and no annotation.

Observations

One irregular lesion rather than a round even macule.
Black, brown, and gray tones sit in the same lesion.
The surface looks shiny and slightly uneven.

Observation prompts

How many dark colors can you name without adding one?
Is the outline round and even, or irregular?

Features, certainty, and weight

Clinical morphology, dermoscopic structure, and image context are separate. An image mark does not compete with a diagnostic structure.

Clinical morphology

Several dark colors — Clearly visible; Major clue

Color mix increases concern. It is not specific and it is not a probability.

Canonical pattern: color-variegation. Educational role: Diagnostic structure. Case certainty and weight stay on this case.

Dermoscopic structure

None stored on this case.

Case-specific observation

None stored on this case.

Context and image information

None stored on this case.

Differential

Cutaneous melanoma

Why it fits: Several dark colors; Irregular outline

Why not: No histopathology sentence is in the caption

The catalog uses this frame as a color example of melanoma.
Seborrheic keratosis

Why it fits: Can be dark and uneven

Why not: Classic stuck-on waxy horns are not the main finding in this frame

Color mix is shared with benign keratinocytic lesions.
Pigmented basal cell carcinoma

Why it fits: Can be irregular and dark

Why not: Leaf-like pigment is not claimed from this clinical photograph

Clinical color is not a dermoscopic structure.

Closest mimic

Seborrheic keratosis

A dark uneven lesion can be a seborrheic keratosis. Classic stuck-on waxy horns are not the main finding here, and color mix alone does not settle the source label.

Why not

None recorded on this case.

Reasoning

The lesion is irregular and contains more than one dark color. The NCI caption calls it melanoma without a histopathology statement.

Several dark colors are clearly visible and are the major clue. They are not specific. The diagnosis is the catalog label. No numeric risk is attached, and no extra color was added to match a mnemonic.

Diagnostic trap

Inventing an extra color to match an ABCD mnemonic.

Mentor note

A duplicate Commons upload of this same photograph was rejected so the curriculum would not repeat one lesion.

Take-home rule

Name only the colors in the frame, then read the source diagnosis.

Management brief

Broad brown patch with an uneven edge (case-g18-04)

Teaching type: Teaching case
Curriculum level: 2 · melanoma
Skills: Variegated plaque, Color variegation
Recorded diagnosis: Cutaneous melanoma
Disease record: cutaneous-melanoma
Confirmation: source_dataset_diagnosis — The NCI description says this slide shows a melanoma on a patient's skin. It does not state subtype, site, or histopathology.
Site: Skin, site not named on the source

Provenance

clinical · Public domain · National Cancer Institute

File: assets/media/cases/case-09-clinical.jpg

Source: National Cancer Institute, via Wikimedia Commons

National Cancer Institute. Public domain.

Modification: other-described — Recompressed for web delivery and file metadata removed. No crop and no annotation.

Observations

A broad brown patch rather than a tiny round macule.
One edge is darker than the rest of the patch.
The outline is scalloped, and the surface is slightly uneven.

Observation prompts

Is this a tiny round macule or a broad patch?
Where is the darker focus relative to the rest of the patch?

Features, certainty, and weight

Clinical morphology, dermoscopic structure, and image context are separate. An image mark does not compete with a diagnostic structure.

Clinical morphology

Broad uneven brown patch — Clearly visible; Major clue

A broad brown patch is not specific. Site and subtype are not in this caption.

Canonical pattern: broad-brown-patch. Educational role: Descriptive morphology, not a dermoscopic structure. Case certainty and weight stay on this case.
Darker focus at one edge — Clearly visible; Supportive

A darker edge is supportive of uneven color. It is not a subtype and not a measurement.

Canonical pattern: peripheral-dark-focus. Educational role: Diagnostic structure. Case certainty and weight stay on this case.

Dermoscopic structure

None stored on this case.

Case-specific observation

None stored on this case.

Context and image information

None stored on this case.

Differential

Cutaneous melanoma

Why it fits: Broad uneven brown patch; Darker focus at one edge

Why not: Subtype and pathology are not in the caption

The NCI caption says melanoma and stops there.
Solar lentigo

Why it fits: A brown patch on skin can be a lentigo

Why not: A lentigo is usually more even in color than this patch

Even color would lean away from this frame. Do not force that lean into a benign label.
Seborrheic keratosis

Why it fits: Can be a broad brown plaque

Why not: A thick stuck-on warty surface is not the dominant look here

Surface texture is the comparison, not a score.

Closest mimic

Solar lentigo

A brown patch is the shared look. This patch is less even than a typical lentigo, and the caption still does not name a subtype.

Why not

None recorded on this case.

Reasoning

The frame is a broad brown patch with a darker edge and a scalloped outline. The NCI text says melanoma without subtype or histopathology.

The broad uneven patch and darker edge are visible. The patch is the major clue and the darker edge is supportive. Diagnostic weight is a short catalog sentence. Missing subtype is a real gap, not a reason to invent one.

Diagnostic trap

Upgrading a generic melanoma caption into superficial spreading or nodular disease.

Mentor note

This is a differentiation case because benign brown patches are the nearby lookalikes. The source does not show dermoscopy.

Take-home rule

Do not invent a subtype the caption does not state.

Management brief

Small pink scaly spot (case-g18-13)

Teaching type: Teaching case
Curriculum level: 2 · mimic
Skills: Small pink scaly spot
Recorded diagnosis: Superficial basal cell carcinoma
Disease record: basal-cell-carcinoma
Confirmation: source_dataset_diagnosis — The NCI description says a pink, scaly lesion and titles it superficial basal cell carcinoma. Histopathology is not stated.
Site: Skin, site not named on the source

Provenance

clinical · Public domain · Kelly Nelson, National Cancer Institute

File: assets/media/cases/case-18-clinical.jpg

Source: National Cancer Institute, via Wikimedia Commons

National Cancer Institute. Public domain.

Modification: other-described — Recompressed for web delivery and file metadata removed. No crop and no annotation.

Observations

A small pink spot, slightly scaly, on otherwise quiet skin.
It is flat to barely raised rather than a large nodule.
A few unrelated-looking brown macules are in the same field.

Observation prompts

Is the pink spot small and flat, or a large nodule?
Can you see scale on it?

Features, certainty, and weight

Clinical morphology, dermoscopic structure, and image context are separate. An image mark does not compete with a diagnostic structure.

Clinical morphology

Small pink scaly spot — Clearly visible; Major clue

Scale on a small pink spot is not specific.

Canonical pattern: pink-scaly-spot. Educational role: Descriptive morphology, not a dermoscopic structure. Case certainty and weight stay on this case.

Dermoscopic structure

None stored on this case.

Case-specific observation

None stored on this case.

Context and image information

None stored on this case.

Differential

Superficial basal cell carcinoma

Why it fits: Small pink scaly spot; NCI title

Why not: No histopathology is stated

The catalog name is the keratinocyte-tumor label.
Amelanotic melanoma

Why it fits: A pink lesion can be a melanoma without pigment

Why not: The source title is basal cell carcinoma

This is why the spot is in the melanoma pathway as a mimic. Size does not remove that line.
Actinic keratosis or dermatitis

Why it fits: Scale on a pink spot can be a keratosis or dermatitis

Why not: The source title is a carcinoma, not dermatitis

Scale is shared. Do not stop at dermatitis because the spot is small.

Closest mimic

Amelanotic melanoma

A pink lesion can be a melanocytic tumor without brown pigment. The source title is a keratinocyte tumor, and that safety line is why the spot is on this pathway.

Why not

None recorded on this case.

Reasoning

A small pink scaly spot is visible. NCI calls it superficial basal cell carcinoma and does not cite histopathology. In this pathway it is a mimic, not a melanoma.

Pink scale on a small spot is clearly visible and is the major clue. The diagnosis is the NCI title. The non-pigmented melanocytic line in the differential is a safety mimic, not a second source diagnosis. Histopathology is not stated.

Diagnostic trap

Dismissing a small pink spot, or calling it melanoma because you are studying melanoma.

Mentor note

The photograph is modest. That is acceptable if the finding you teach is actually there.

Take-home rule

A small pink scaly spot still has a melanoma line and a keratinocyte-tumor line.

Management brief

Large plantar pigmented macule (case-acral-melanoma-plantar)

Teaching type: Teaching case
Curriculum level: 2 · melanoma
Skills: Acral pigment, Asymmetry
Recorded diagnosis: Acral lentiginous melanoma
Disease record: acral-melanoma
Confirmation: histopathology — Source paper reports histopathology-confirmed acral lentiginous melanoma after complete histological analysis of the specimen (Clark IV, Breslow 2.6 mm). Docutis does not re-interpret slides.
Site: Plantar foot / toe

Provenance

clinical · CC BY 4.0 · Xavier-Júnior, José; Munhoz, Tania; Souza, Vinicius; Campos, Eloísa; Stolf, Hamilton; Marques, Mariângela

File: assets/media/cases/acral-melanoma-plantar-clinical.jpg

Source: Xavier-Júnior et al., Diagnostic Pathology (2015), via Wikimedia Commons

Xavier-Júnior et al. 2015, Diagnostic Pathology. CC BY 4.0. https://doi.org/10.1186/s13000-015-0307-z

Modification: unmodified

Observations

Large pigmented macule on plantar/acral skin.
Asymmetry of overall shape.
Irregular borders.
Color variegation with dark-brown areas and additional tones.

Observation prompts

Legacy pilot. No new prompt field was added, so the governed payload stays unchanged.

Features, certainty, and weight

Clinical morphology, dermoscopic structure, and image context are separate. An image mark does not compete with a diagnostic structure.

Clinical morphology

None stored on this case.

Dermoscopic structure

None stored on this case.

Case-specific observation

None stored on this case.

Context and image information

None stored on this case.

Differential

Acral nevus

Why it fits: Pigmented macule on acral skin

Why not: Large size; Marked asymmetry; Irregular borders; Color variegation

Most acral nevi are smaller and more orderly; progressive large asymmetric variegated patches warrant specialist assessment.
Acral lentiginous melanoma

Why it fits: Acral site; Asymmetry; Irregular borders; Color variegation

Why not: Not recorded

This published case was histopathologically confirmed as acral lentiginous melanoma.
Subungual/trauma-related hemorrhage (if periungual)

Why it fits: Acral location can host hemorrhage

Why not: Broad macular pigment pattern with variegation beyond a typical hematoma streak

Hemorrhage usually has a history of trauma and evolving clearance; do not dismiss concerning acral pigment without examination.

Closest mimic

Not stored on this legacy pilot.

Why not

None recorded on this case.

Reasoning

Diagnostic trap

Mentor note

Take-home rule

Management brief

Open the Docutis acral melanoma record for structured reference context after you finish the case.

Small eroded spot on the ear (case-g18-14)

Teaching type: Teaching case
Curriculum level: 2 · mimic
Skills: Eroded papule
Recorded diagnosis: Ulcerated basal cell carcinoma
Disease record: basal-cell-carcinoma
Confirmation: source_dataset_diagnosis — The NCI description says a red, ulcerated lesion on the right ear with a white border and calls it ulcerated basal cell carcinoma with a pearly rim. Histopathology is not stated. The erosion is the obvious finding; a pearly rim is the caption's phrase and is not upgraded beyond that.
Site: Ear

Provenance

clinical · Public domain · Kelly Nelson, National Cancer Institute

File: assets/media/cases/case-19-clinical.jpg

Source: National Cancer Institute, via Wikimedia Commons

National Cancer Institute. Public domain.

Modification: other-described — Recompressed for web delivery and file metadata removed. No crop and no annotation.

Observations

The frame is an ear held by fingers, with hair at the edge.
A small red eroded spot is on the ear.
The spot is focal rather than a large ulcer.

Observation prompts

Is the red spot a small erosion or a large ulcer?
What else is in the frame that is not the spot?

Features, certainty, and weight

Clinical morphology, dermoscopic structure, and image context are separate. An image mark does not compete with a diagnostic structure.

Clinical morphology

Small erosion on the ear — Clearly visible; Major clue

A small erosion is not specific.

Canonical pattern: small-erosion. Educational role: Descriptive morphology, not a dermoscopic structure. Case certainty and weight stay on this case.

Dermoscopic structure

None stored on this case.

Case-specific observation

None stored on this case.

Context and image information

None stored on this case.

Differential

Ulcerated basal cell carcinoma

Why it fits: Small red erosion on the ear; NCI title

Why not: Histopathology is not stated

The catalog name includes ulcerated basal cell carcinoma. Pearly rim is caption language.
Amelanotic melanoma

Why it fits: A red eroded papule can be a melanoma without pigment

Why not: The source title is basal cell carcinoma

Ear lesions are a classic place not to drop the melanoma line.
Chondrodermatitis or traumatized skin

Why it fits: The ear is easy to injure

Why not: The source title is a carcinoma

Pain and a history of pressure are not in this caption.

Closest mimic

Amelanotic melanoma

A red eroded papule on the ear can be a non-pigmented melanocytic tumor. The source title is a keratinocyte tumor, and the melanoma line stays because the site is a classic place not to drop it.

Why not

None recorded on this case.

Reasoning

A small red erosion is visible on an ear. NCI calls it ulcerated basal cell carcinoma and mentions a pearly rim. Histopathology is not stated. It is a mimic in this pathway.

The small erosion and the ear site are clearly visible. The erosion is the major clue. A pearly rim has weight only as caption text, not as a structure drawn on the image. Histopathology is not stated. The non-pigmented melanocytic differential is a safety line, not a second label.

Diagnostic trap

Calling every ear papule a basal cell carcinoma and dropping melanoma, or claiming a pearly rim you cannot see.

Mentor note

The partial ear and hair are not a named portrait. No name is in the file.

Take-home rule

On the ear, describe the erosion and keep both a keratinocyte tumor and a non-pigmented melanoma in mind.

Management brief

Nodular lesion dermatoscopy with vessels (case-bcc-nodular-dermoscopy)

Teaching type: Teaching case
Curriculum level: 2 · mimic
Skills: Branching vessels, Pink nodule
Recorded diagnosis: Nodular basal cell carcinoma
Disease record: basal-cell-carcinoma
Confirmation: expert_diagnosis — Source Commons description labels the image as dermatoscopy of a nodular basal cell carcinoma by the clinician author. Histopathology is not cited on the Commons page; do not claim histo confirmation here.
Site: Not specified on source (dermoscopic close-up)

Provenance

dermoscopy · CC BY 4.0 · Dr. Thomas Brinkmeier

File: assets/media/cases/bcc-nodular-wikiderm-dermoscopy.jpg

Source: Dr. Thomas Brinkmeier / WIKIDERM, via Wikimedia Commons

Dr. Thomas Brinkmeier, WIKIDERM. CC BY 4.0.

Modification: other-described — Resized and recompressed for web delivery (max width 1600 px); no clinical cropping or annotation added.

Observations

Focused dermoscopic field of a nodular lesion.
Branching / telangiectatic vascular structures are visible.
Translucent to pink structural background without a regular pigment network of a banal nevus.

Observation prompts

Legacy pilot. No new prompt field was added, so the governed payload stays unchanged.

Features, certainty, and weight

Clinical morphology, dermoscopic structure, and image context are separate. An image mark does not compete with a diagnostic structure.

Clinical morphology

None stored on this case.

Dermoscopic structure

None stored on this case.

Case-specific observation

None stored on this case.

Context and image information

None stored on this case.

Differential

Basal cell carcinoma (nodular)

Why it fits: Branching vessels; Translucent vascularized nodule pattern

Why not: Not recorded

Author-labeled nodular BCC; vascular clues are the teaching focus.
Amelanotic / hypomelanotic melanoma

Why it fits: Can show atypical vessels

Why not: Classic arborizing BCC-type vessels and translucent BCC pattern favor BCC in this labeled example

Always keep amelanotic melanoma in mind for atypical pink lesions; confirmation pathway is clinical-pathologic, not image quiz alone.
Sebaceous hyperplasia / other adnexal nodule

Why it fits: Facial/nodular pink lesions can mimic

Why not: Crown vessels of sebaceous hyperplasia differ from arborizing BCC vessels

Vessel morphology and overall pattern help, but uncertain lesions need clinicopathologic correlation.

Closest mimic

Not stored on this legacy pilot.

Why not

None recorded on this case.

Reasoning

Diagnostic trap

Mentor note

Take-home rule

Management brief

Compare with the Docutis basal cell carcinoma record and the BCC clues schematic after the case.

Brown lesion with a pale center (case-g18-05)

Teaching type: Reasoning case
Curriculum level: 3 · melanoma
Skills: Pale area inside pigment, Border irregularity
Recorded diagnosis: Cutaneous melanoma
Disease record: cutaneous-melanoma
Confirmation: source_dataset_diagnosis — The NCI description titles the image melanoma and repeats an ABCD sentence about asymmetry, border, color, and diameter. It does not state histopathology, and it does not use the word regression. The pale center is described here only as color.
Site: Skin, site not named on the source

Provenance

clinical · Public domain · Larry Meyer, National Cancer Institute

File: assets/media/cases/case-10-clinical.jpg

Source: National Cancer Institute, via Wikimedia Commons

National Cancer Institute. Public domain.

Modification: other-described — Recompressed for web delivery and file metadata removed. No crop and no annotation.

Observations

A brown-black lesion with an irregular outline.
The center is paler than the rim.
Fine hairs cross the field. No scale bar is visible.

Observation prompts

How does the center compare with the rim?
What name are you tempted to give the pale center, and is that name written in the title?

Features, certainty, and weight

Clinical morphology, dermoscopic structure, and image context are separate. An image mark does not compete with a diagnostic structure.

Clinical morphology

Pale center inside a darker rim — Clearly visible; Major clue

Pallor is not specific and is not a synonym for a histologic process in this title.

Canonical pattern: pale-center. Educational role: Diagnostic structure. Case certainty and weight stay on this case.

Dermoscopic structure

None stored on this case.

Case-specific observation

A histologic name for the pale center — Not visible in this image; Conflicts with a simple reading

The NCI title does not give the pale center a histologic name. Do not supply one.

Canonical pattern: not linked. The case records that the source gives the pale center no histologic name. That absence is not a reusable visual pattern.

Context and image information

None stored on this case.

Differential

Cutaneous melanoma

Why it fits: Irregular brown-black rim; Source catalog label

Why not: No pathology report is cited

The NCI title is melanoma. The pale center is not given a histologic name in that title.
Lichenoid keratosis or inflamed benign lesion

Why it fits: A pale or pink center can be inflammation

Why not: The source does not describe inflammation

Pallor has more than one reading.
Scar or treated site

Why it fits: A pale center can be a scar

Why not: No treatment history is in the caption

Do not invent a procedure that is not in the source.

Closest mimic

Lichenoid keratosis or inflamed benign lesion

A pale center can be inflammation or a treated site. The source does not describe either, and it also does not give the pale center a histologic name.

Why not

None recorded on this case.

Reasoning

An irregular brown-black lesion has a paler center. The NCI title is melanoma. The repeated ABCD sentence is not a measurement and not histopathology.

The pale center is clearly visible and is the major clue as a color finding. A histologic name for that center is not in the source, so it gets conflicting weight: it must not be added. The repeated ABCD sentence is not a measurement. The diagnosis weight is the catalog title.

Diagnostic trap

Calling every pale center regression, or trusting a boilerplate ABCD line as if each letter were measured.

Mentor note

This photograph is smaller and softer than the other NCI frames. Teach only what remains visible.

Take-home rule

A pale center is a color finding until the source gives it another name.

Management brief

Red nodule beside a dark macule (case-g18-06)

Teaching type: Reasoning case
Curriculum level: 3 · melanoma
Skills: Nodule beside a macule
Recorded diagnosis: Superficial spreading melanoma with a contiguous nodule
Disease record: cutaneous-melanoma
Confirmation: source_dataset_diagnosis — The NCI description says this is advanced malignant melanoma, with a plaque of radial-growth superficial spreading melanoma beside a pink amelanotic nodule of vertical growth. It does not use the word histopathology. A general sentence in that caption about prognosis and death is a textbook statement, not an outcome recorded for this person, and it is not repeated as this patient's course. The teaching file is cropped to drop handwritten ruler identifiers.
Site: Skin, site not named on the source

Provenance

clinical · Public domain · National Cancer Institute

File: assets/media/cases/case-11-clinical.jpg

Source: National Cancer Institute, via Wikimedia Commons

National Cancer Institute. Public domain.

Modification: cropped — Cropped to remove the ruler and handwritten specimen identifiers, then recompressed. The nodule and adjacent dark macule were kept. No annotation was added.

Observations

A shiny red nodule is the most raised part of the field.
A smaller dark brown macule sits against that nodule.
Black marker ink outlines the area. The original ruler is not in this file.

Observation prompts

How many separate skin findings are inside the inked field?
Which marks are ink rather than skin?

Features, certainty, and weight

Clinical morphology, dermoscopic structure, and image context are separate. An image mark does not compete with a diagnostic structure.

Clinical morphology

Red nodule touching a dark macule — Clearly visible; Major clue

The combination is concerning and not specific until the source is read.

Canonical pattern: nodule-beside-pigmented-macule. Educational role: Diagnostic structure. Case certainty and weight stay on this case.

Dermoscopic structure

None stored on this case.

Case-specific observation

None stored on this case.

Context and image information

Marker ink around the field — Clearly visible; Conflicts with a simple reading

Ink is not a clinical border. Treating it as skin gives it conflicting weight.

Canonical pattern: marker-ink. Educational role: Image mark, not a skin finding. Case certainty and weight stay on this case.

Differential

Superficial spreading melanoma with a contiguous nodule

Why it fits: Red nodule beside darker pigment; NCI description of radial and vertical growth

Why not: The caption does not say histopathology

Use the source's own names after reveal. Do not add a Breslow number.
Pigmented lesion with a separate angioma

Why it fits: A red shiny papule can be vascular

Why not: The source describes one contiguous lesion, not two unrelated lesions

Contiguity is the teaching point of the caption.
Nodular basal cell carcinoma

Why it fits: A red nodule can be a keratinocyte tumor

Why not: The source text is melanoma, not basal cell carcinoma

A pink nodule is exactly where the mimic matters.

Closest mimic

Nodular basal cell carcinoma

A shiny red nodule is where a keratinocyte tumor remains realistic. The source describes one contiguous lesion and does not cite histopathology.

Why not

None recorded on this case.

Reasoning

The cropped frame shows a shiny red nodule against a dark macule inside marker ink. NCI calls this advanced melanoma with a superficial spreading component and an amelanotic nodule. Histopathology is not stated.

The red nodule and the dark macule are clearly visible and together are the major clue. Marker ink is clearly visible and conflicting if you read it as a border. Growth-phase names have weight only as NCI wording. The prognostic sentence in the same caption is not evidence about this patient. Histopathology has no weight because it is absent.

Diagnostic trap

Reading marker ink as a clinical border, or quoting the caption's general death sentence as this patient's result.

Mentor note

The crop removed initials and a date. It also removed the scale. Do not estimate millimeters from memory of the uncropped file.

Take-home rule

A pink nodule beside pigment is described as two findings. Growth-phase labels belong to the source text.

Management brief

Shiny red papule on hair-bearing skin (case-g18-15)

Teaching type: Teaching case
Curriculum level: 3 · mimic
Skills: Shiny red papule
Recorded diagnosis: Basal cell carcinoma
Disease record: basal-cell-carcinoma
Confirmation: source_dataset_diagnosis — The NCI description says a small reddish or brownish papule, often with telangiectatic vessels, which may look translucent or pearly, with a possible central depression and rolled borders. The title context is basal cell carcinoma. Histopathology is not stated in that caption. Telangiectasia and a pearly quality are caption language; this teaching note does not claim every one of those structures is obvious after the crop.
Site: Lower back, according to the source label

Provenance

clinical · Public domain · National Cancer Institute

File: assets/media/cases/case-20-clinical.jpg

Source: National Cancer Institute, via Wikimedia Commons

National Cancer Institute. Public domain.

Modification: cropped — Cropped to remove the handwritten date and site label, then recompressed. The red papule was kept. No annotation was added. The source text places the lesion on the lower back.

Observations

A solitary shiny red papule on hair-bearing skin.
The papule is round and raised, with a bright uneven top.
The handwritten card and ruler from the original file are not in this crop.

Observation prompts

Is the papule solitary, shiny, and red?
Which parts of the original file are missing from this crop?

Features, certainty, and weight

Clinical morphology, dermoscopic structure, and image context are separate. An image mark does not compete with a diagnostic structure.

Clinical morphology

Solitary shiny red papule — Clearly visible; Major clue

A shiny red papule is not specific.

Canonical pattern: shiny-red-papule. Educational role: Descriptive morphology, not a dermoscopic structure. Case certainty and weight stay on this case.

Dermoscopic structure

Vessels on the papule — Uncertain; Weak

Count a vessel only if you can see it. The caption mentions vessels as a general feature, which is not the same as a vessel you have confirmed.

Canonical pattern: surface-vessels. Educational role: Diagnostic structure. Case certainty and weight stay on this case.

Case-specific observation

None stored on this case.

Context and image information

None stored on this case.

Differential

Basal cell carcinoma

Why it fits: Shiny red papule; NCI description of a basal cell carcinoma papule

Why not: Histopathology is not stated; Not every caption feature is equally obvious

The source diagnosis is the keratinocyte tumor. Do not add vessels you are unsure about.
Amelanotic melanoma

Why it fits: A red papule can be a melanoma without pigment

Why not: The source text describes basal cell carcinoma

This mimic relationship is the reason the case is in the pathway.
Pyogenic granuloma

Why it fits: A bright red papule can be a pyogenic granuloma

Why not: The source text is basal cell carcinoma

A moist bleeding papule overlaps. A collarette is not recorded as the main finding here.

Closest mimic

Amelanotic melanoma

A solitary red papule can be a melanocytic tumor without pigment. The source text describes a keratinocyte tumor, which is why both lines stay open.

Why not

None recorded on this case.

Reasoning

A shiny red papule remains after the label was cropped off. NCI describes a basal cell carcinoma papule and mentions vessels and a pearly look as general features. Histopathology is not stated.

The shiny red papule is clearly visible and is the major clue. Vessels are uncertain in this crop, so they stay weak and are not confirmed. Caption phrases about pearliness are not given extra weight beyond what a viewer can confirm. The site is source text because the card was removed. Histopathology is not stated.

Diagnostic trap

Inventing telangiectasia to match a textbook sentence, or forgetting melanoma because the papule is red.

Mentor note

The crop is a de-identification edit of a date card, not a clinical annotation.

Take-home rule

A shiny red papule keeps amelanotic melanoma in the differential even when the source says basal cell carcinoma.

Management brief

Pigmented lesion dermatoscopy on the back (case-bcc-pigmented-dermoscopy)

Teaching type: Teaching case
Curriculum level: 3 · mimic
Skills: Pigment architecture
Recorded diagnosis: Pigmented basal cell carcinoma
Disease record: basal-cell-carcinoma
Confirmation: expert_diagnosis — Source Commons description labels the image as dermatoscopy of a pigmented basal cell carcinoma on the back. Histopathology is not cited on the Commons page.
Site: Back (per source description)

Provenance

dermoscopy · CC BY 4.0 · Dr. Thomas Brinkmeier

File: assets/media/cases/bcc-pigmented-wikiderm-dermoscopy.jpg

Source: Dr. Thomas Brinkmeier / WIKIDERM, via Wikimedia Commons

Dr. Thomas Brinkmeier, WIKIDERM. CC BY 4.0.

Modification: other-described — Resized and recompressed for web delivery (max width 1600 px); no clinical cropping or annotation added.

Observations

Pigmented dermoscopic structures within a focal lesion on truncal skin context.
Asymmetric distribution of pigment.
Leaf-like or ovoid pigment aggregates rather than a regular reticular melanocytic network.

Observation prompts

Legacy pilot. No new prompt field was added, so the governed payload stays unchanged.

Features, certainty, and weight

Clinical morphology, dermoscopic structure, and image context are separate. An image mark does not compete with a diagnostic structure.

Clinical morphology

None stored on this case.

Dermoscopic structure

None stored on this case.

Case-specific observation

None stored on this case.

Context and image information

None stored on this case.

Differential

Pigmented basal cell carcinoma

Why it fits: Leaf-like / ovoid pigment aggregates; Absent regular nevus network

Why not: Not recorded

Author-labeled pigmented BCC; emphasize BCC pigment structures vs melanocytic network.
Melanoma

Why it fits: Asymmetric pigment; Color variegation potential

Why not: Classic BCC-specific pigment structures favor BCC when clearly present

When uncertain, treat as a pigmented lesion requiring clinicopathologic correlation — never use this module as a diagnostic oracle.
Seborrheic keratosis

Why it fits: Can be pigmented on the trunk

Why not: Milia-like cysts / comedo-like openings pattern differs from BCC leaf-like structures

Compare global pattern; SK clues differ from BCC pigment architecture.

Closest mimic

Not stored on this legacy pilot.

Why not

None recorded on this case.

Reasoning

Diagnostic trap

Mentor note

Take-home rule

Management brief

Review the Docutis basal cell carcinoma record after completing differentials.

Flat brown area beside a blue-black papule (case-g18-07)

Teaching type: Reasoning case
Curriculum level: 3 · melanoma
Skills: Flat area with a raised focus, Pale area inside pigment
Recorded diagnosis: Superficial spreading melanoma arising from a dysplastic nevus
Disease record: cutaneous-melanoma
Confirmation: source_dataset_diagnosis — The NCI description says superficial spreading melanoma arising from a dysplastic nevus, identifies the 4-by-8-mm pink-tan area at the arrow as the nevus, calls the blue-black area invasive melanoma, and calls the gray area regression. It does not state histopathology. The 4-by-8-mm figure is the caption's measurement, not a new measurement.
Site: Skin, site not named on the source

Provenance

clinical · Public domain · National Cancer Institute

File: assets/media/cases/case-12-clinical.jpg

Source: National Cancer Institute, via Wikimedia Commons

National Cancer Institute. Public domain.

Modification: other-described — Recompressed for web delivery and file metadata removed. No crop and no annotation.

Observations

A printed arrow points at a flatter brown-pink area.
A blue-black raised area with an uneven edge sits next to that flat area.
A gray zone lies along the lower left of the dark area.

Observation prompts

What does the printed arrow point at?
Which area is raised, and which area looks gray?

Features, certainty, and weight

Clinical morphology, dermoscopic structure, and image context are separate. An image mark does not compete with a diagnostic structure.

Clinical morphology

Flat area, raised dark focus, and gray zone — Clearly visible; Major clue

Gray color is not specific. A histologic word for the gray area belongs to the caption, not to the gray color alone.

Canonical pattern: flat-area-with-raised-focus. Educational role: Diagnostic structure. Case certainty and weight stay on this case.

Dermoscopic structure

None stored on this case.

Case-specific observation

None stored on this case.

Context and image information

Printed arrow — Clearly visible; Weak

The arrow is already in the public-domain file. It is a pointer, not a skin finding, so its weight is weak.

Canonical pattern: printed-pointer. Educational role: Image mark, not a skin finding. Case certainty and weight stay on this case.

Differential

Superficial spreading melanoma arising in a dysplastic nevus

Why it fits: Flat area at the printed arrow; Blue-black raised area; NCI caption

Why not: Histopathology is not stated

After reveal, keep the caption's names attached to the areas they name.
Melanoma without a precursor nevus

Why it fits: A dark raised lesion can stand alone

Why not: The caption specifically describes a nevus at the arrow

Do not drop the flat component just because the dark papule dominates.
Pigmented basal cell carcinoma

Why it fits: Irregular dark pigment

Why not: The caption is not a basal cell carcinoma label

Clinical color does not show leaf-like structures.

Closest mimic

Pigmented basal cell carcinoma

Irregular dark pigment can be a pigmented keratinocyte tumor. This clinical frame does not show leaf-like structures, and the caption is not that label.

Why not

None recorded on this case.

Reasoning

The photograph shows a flat brown-pink area at a printed arrow, a blue-black raised area, and a gray zone. NCI calls this superficial spreading melanoma arising in a dysplastic nevus and calls the gray area regression, without a histopathology sentence.

Three colors and shapes are clearly visible and are the major clue. The printed arrow is visible and weak: it is not skin. The 4-by-8-mm measurement and the caption's word for the gray area have weight only as caption text. Histopathology has no weight because it is absent.

Diagnostic trap

Adding your own arrow, or treating regression as a diagnosis you made from gray color.

Mentor note

The arrow is a derivative already present in the public-domain file. Docutis did not draw it.

Take-home rule

Map each caption phrase to the area it names. Do not merge them into one word.

Management brief

Pink nodule inside a drape (case-g18-10)

Teaching type: Reasoning case
Curriculum level: 4 · melanoma
Skills: Pink nodule
Recorded diagnosis: Amelanotic melanoma
Disease record: cutaneous-melanoma
Confirmation: expert_diagnosis — The Commons description by Dr. Thomas Brinkmeier calls this a macroscopic image of an amelanotic malignant melanoma. Histopathology is not cited. The source does not say the word nodular as a subtype, so nodular subtype is not added even though the lesion is raised. This file is not paired with the separate dermoscopic photograph, because the source does not say they are the same lesion.
Site: Skin, site not named on the source

Provenance

clinical · CC BY 4.0 · Dr. Thomas Brinkmeier

File: assets/media/cases/case-15-clinical.jpg

Source: Dr. Thomas Brinkmeier / WIKIDERM, via Wikimedia Commons

Dr. Thomas Brinkmeier, WIKIDERM. CC BY 4.0.

Modification: other-described — Resized and recompressed for web delivery (max width 1600 px) and file metadata removed. No crop and no annotation.

Observations

A shiny pink nodule without brown pigment in the nodule itself.
The surface looks moist, and a little pinkness is at the base.
A blue drape surrounds the field. A few small brown macules are on nearby skin.

Observation prompts

Is there brown pigment inside the nodule itself?
What else around the nodule is drape or background skin?

Features, certainty, and weight

Clinical morphology, dermoscopic structure, and image context are separate. An image mark does not compete with a diagnostic structure.

Clinical morphology

Pink nodule without pigment — Clearly visible; Major clue

Lack of pigment is not reassuring and is not specific.

Canonical pattern: pink-nodule-without-pigment. Educational role: Descriptive morphology, not a dermoscopic structure. Case certainty and weight stay on this case.

Dermoscopic structure

None stored on this case.

Case-specific observation

None stored on this case.

Context and image information

None stored on this case.

Differential

Amelanotic melanoma

Why it fits: Pink nodule; Clinician-authored label of amelanotic melanoma

Why not: No histopathology is cited; Subtype is not stated

Rank the author's diagnosis first after you have described the lack of pigment.
Nodular basal cell carcinoma

Why it fits: A pink nodule is a common keratinocyte-tumor look

Why not: The author label is melanoma, not basal cell carcinoma

This is the main mimic. Vessel clues are not available in this clinical file.
Pyogenic granuloma

Why it fits: A moist red nodule can be a pyogenic granuloma

Why not: The author label is melanoma

Bleeding friable nodules overlap. The photograph does not show a collar of scale clearly enough to prefer granuloma.

Closest mimic

Nodular basal cell carcinoma

A pink nodule is the common keratinocyte-tumor look. Vessel clues are not available in this clinical file, and the author label is what ranks the source diagnosis.

Why not

Nodular basal cell carcinoma — A pink nodule is a basal cell carcinoma until proven otherwise in many clinics. Here the author label is amelanotic melanoma, and this clinical frame does not show branching vessels. That does not make the mimic impossible.
Pyogenic granuloma — A moist red nodule suggests a pyogenic granuloma. A collarette is not clearly recorded in this description, and the source diagnosis is melanoma. Friability alone would not decide it.

Reasoning

A shiny pink nodule sits in a drape. Dr. Thomas Brinkmeier labels it amelanotic melanoma. Histopathology and histologic subtype are not stated. A separate dermoscopic file was not assumed to be the same lesion.

The pink nodule without brown pigment in the nodule is clearly visible and is the major clue. The diagnosis weight is an expert author label. Histopathology has no weight. Nearby brown macules are background, not part of the nodule. No subtype is stated.

Diagnostic trap

Reassuring yourself because the lesion is not brown, or pairing it with an unmatched dermoscopic image.

Mentor note

CC BY 4.0 allows a resized derivative. The note records the resize. No marks were drawn.

Take-home rule

A pink nodule still needs a melanoma line in the differential. Pigment is not required.

Management brief

Pink field with more than one vessel shape (case-g18-11)

Teaching type: Expert-challenge case
Curriculum level: 4 · melanoma
Skills: More than one vessel shape, Evidence weighting
Recorded diagnosis: Amelanotic melanoma
Disease record: cutaneous-melanoma
Confirmation: expert_diagnosis — The Commons description calls this a dermoscopic image of an amelanotic malignant melanoma. Histopathology is not cited. The white circle and 0-10 scale are in the source image. This file is not paired with the clinical nodule photograph, because the source does not state they are the same lesion and the shapes do not match.
Site: Not specified; dermoscopic close-up

Provenance

dermoscopy · CC BY 4.0 · Dr. Thomas Brinkmeier

File: assets/media/cases/case-16-dermoscopy.jpg

Source: Dr. Thomas Brinkmeier / WIKIDERM, via Wikimedia Commons

Dr. Thomas Brinkmeier, WIKIDERM. CC BY 4.0.

Modification: other-described — Resized and recompressed for web delivery (max width 1600 px) and file metadata removed. No crop and no annotation.

Observations

A round dermoscopic field of pink skin.
Red vessels include both dots and short irregular lines, mostly around a paler pink center.
A white circular mark and a 0 to 10 scale are printed in the image.

Observation prompts

Are the red vessels one shape or more than one?
Which marks are a printed circle or a scale, rather than skin?

Features, certainty, and weight

Clinical morphology, dermoscopic structure, and image context are separate. An image mark does not compete with a diagnostic structure.

Clinical morphology

None stored on this case.

Dermoscopic structure

Mixed vessel shapes on pink skin — Clearly visible; Major clue

Mixed vessels raise concern. They are not specific for one tumor and they are not a probability.

Canonical pattern: polymorphous-vessels. Educational role: Diagnostic structure. Case certainty and weight stay on this case.

Case-specific observation

None stored on this case.

Context and image information

Printed circle and scale — Clearly visible; Conflicts with a simple reading

The circle and the scale are printed in the file. They are not shiny lines and not a skin finding.

Canonical pattern: printed-circle-and-scale. Educational role: Image mark, not a skin finding. Case certainty and weight stay on this case.

Differential

Amelanotic melanoma

Why it fits: More than one vessel shape; Author label of amelanotic melanoma

Why not: Vessels are not specific; No histopathology is cited

The author label is the diagnosis. The vessels are the clue, not proof.
Basal cell carcinoma

Why it fits: Pink field with vessels

Why not: Classic branching vessels are not the pattern described here

Compare vessel shape. Branching vessels would push attention toward basal cell carcinoma; mixed dots and lines do not settle it.
Inflamed benign lesion

Why it fits: Dotted vessels occur in inflamed skin

Why not: The author label is melanoma

Dotted vessels alone are a famous false friend.

Closest mimic

Basal cell carcinoma

A pink field with vessels keeps a keratinocyte tumor in view. Branching vessels are not the pattern described here, and mixed dots and lines do not settle the author label.

Why not

Basal cell carcinoma — A pink dermoscopic field can be basal cell carcinoma. This frame's vessels are mixed dots and lines rather than a single arborizing tree, which argues against using basal cell carcinoma as the only reading. It does not exclude it.
Inflamed benign skin — Dotted vessels are common in inflamed benign lesions. The author label is melanoma, and a paler center with irregular lines is why inflammation is not the whole story. Vessel pattern is not specific.

Reasoning

Dermoscopy shows dotted and linear red vessels around a paler pink center, plus a printed circle and scale. The author calls it amelanotic melanoma. Histopathology is not cited, and this is not merged with the clinical nodule file.

Dotted and linear red vessels are clearly visible and are the major clue. They are not specific, so they do not carry the diagnosis. The author label carries the diagnosis. The printed circle and scale are visible and conflicting if you treat them as structures. Histopathology is not cited.

Diagnostic trap

Treating any pink vessel pattern as basal cell carcinoma, or treating the printed circle as shiny white lines.

Mentor note

If you cannot tell dotted from linear in this file, say so. Do not invent milky-red globules.

Take-home rule

More than one vessel shape is a clue and it is not specific. Read the source diagnosis separately.

Management brief

Brown patch beside a skin crease (case-g18-09)

Teaching type: Reasoning case
Curriculum level: 4 · melanoma
Skills: Change is not in one frame, Border irregularity
Recorded diagnosis: Cutaneous melanoma
Disease record: cutaneous-melanoma
Confirmation: source_dataset_diagnosis — The NCI description says this is melanoma whose diameter had changed, as part of an ABCD set. A changed diameter is not visible in one photograph. Histopathology is not stated.
Site: Skin beside a crease; the source does not name the site

Provenance

clinical · Public domain · National Cancer Institute

File: assets/media/cases/case-14-clinical.jpg

Source: National Cancer Institute, via Wikimedia Commons

National Cancer Institute. Public domain.

Modification: other-described — Recompressed for web delivery and file metadata removed. No crop and no annotation.

Observations

An irregular brown patch lies next to a skin crease.
The patch is darker in the center than at some edges.
A separate small red macule sits nearby. Only one date is in the file.

Observation prompts

Can this single frame show that a diameter changed?
Is the small red macule part of the brown patch, or separate?

Features, certainty, and weight

Clinical morphology, dermoscopic structure, and image context are separate. An image mark does not compete with a diagnostic structure.

Clinical morphology

Irregular brown patch — Clearly visible; Major clue

An irregular brown patch is not specific. Change in size is not visible in one frame.

Canonical pattern: irregular-brown-patch. Educational role: Descriptive morphology, not a dermoscopic structure. Case certainty and weight stay on this case.

Dermoscopic structure

None stored on this case.

Case-specific observation

None stored on this case.

Context and image information

A second date showing a smaller patch — Not visible in this image; Conflicts with a simple reading

The caption says the diameter had changed. This file has only one date.

Canonical pattern: change-outside-one-frame. Educational role: Context, not a diagnostic structure. Case certainty and weight stay on this case.

Differential

Cutaneous melanoma

Why it fits: Irregular brown patch; NCI statement that the diameter had changed

Why not: Change is not visible in this single frame; No histopathology sentence

The diagnosis and the history of change are both source text.
Seborrheic keratosis

Why it fits: A brown rough patch near a crease can be a seborrheic keratosis

Why not: The source label is melanoma

Stuck-on lesions are the mimic. This frame does not show a thick warty plate clearly enough to prefer that mimic over the source.
Solar lentigo

Why it fits: Brown patch on sun-exposed-looking skin

Why not: The center is darker and less uniform than a typical even lentigo

Evenness would support a lentigo. It is not what dominates here, and it would still not erase the source label.

Closest mimic

Seborrheic keratosis

A brown patch near a crease can be a seborrheic keratosis. This frame does not show a thick warty plate clearly enough to prefer that mimic over the source label.

Why not

Seborrheic keratosis — A brown patch can be a seborrheic keratosis. This frame does not show a thick waxy, stuck-on surface as its main feature, and the source calls the lesion melanoma. That is not a probability.
Solar lentigo — A lentigo is usually a more even brown patch. The darker center argues against stopping at a lentigo, but a single photo still does not show the diameter change the caption mentions.

Reasoning

An irregular brown patch is visible beside a crease, with a separate small red macule. NCI calls the lesion melanoma and says the diameter had changed. The change is not in the image.

Border and color are clearly visible and are the major clue. A second date is not in the file, so visible growth gets conflicting weight: do not pretend to see it. History of growth has weight only as caption text. A nearby red macule is a separate finding, not proof of growth.

Diagnostic trap

Narrating growth you cannot see, or ignoring a stated history because the picture is static.

Mentor note

The small red spot is in the frame. Do not fold it into the brown patch without a reason.

Take-home rule

One photograph cannot show that a diameter changed.

Management brief

Single dark papule with a brown edge (case-g18-08)

Teaching type: Expert-challenge case
Curriculum level: 4 · melanoma
Skills: Evidence weighting, Change is not in one frame
Recorded diagnosis: Invasive melanoma arising in a dysplastic nevus
Disease record: cutaneous-melanoma
Confirmation: source_dataset_diagnosis — The NCI text says a 40-year-old woman in a melanoma-prone family had moles on the back photographed for follow-up, and that 18 months later the upper nevus had a new 3-mm black nodule which proved to be invasive malignant melanoma arising in a dysplastic nevus. The word histopathology is not used. The file in this case is a single close-up. The earlier cluster, the arrow, and the 18-month interval are narrative, not a second picture here. Age and sex are the source's demographic statement, not identifiers read from the frame.
Site: Back, according to the source narrative

Provenance

clinical · Public domain · National Cancer Institute

File: assets/media/cases/case-13-clinical.jpg

Source: National Cancer Institute, via Wikimedia Commons

National Cancer Institute. Public domain.

Modification: other-described — Recompressed for web delivery and file metadata removed. No crop and no annotation.

Observations

One dark blue-black papule.
Brown pigment extends irregularly from that papule.
No second date, no arrow, and no cluster of other moles is visible in this file.

Observation prompts

How many dates or earlier photographs are in this file?
What can you say about change from this frame alone?

Features, certainty, and weight

Clinical morphology, dermoscopic structure, and image context are separate. An image mark does not compete with a diagnostic structure.

Clinical morphology

Single dark papule — Clearly visible; Major clue

A dark papule is not specific. Change over time is not visible here.

Canonical pattern: solitary-dark-papule. Educational role: Descriptive morphology, not a dermoscopic structure. Case certainty and weight stay on this case.

Dermoscopic structure

None stored on this case.

Case-specific observation

None stored on this case.

Context and image information

An earlier photograph of the same papule — Not visible in this image; Conflicts with a simple reading

The narrative describes change. This file does not contain the earlier look.

Canonical pattern: change-outside-one-frame. Educational role: Context, not a diagnostic structure. Case certainty and weight stay on this case.

Differential

Invasive melanoma arising in a dysplastic nevus

Why it fits: Dark papule with irregular brown edge; NCI statement that the nodule proved to be invasive melanoma

Why not: The follow-up pair is not in this file; Histopathology is not named

Rank this first because of the source narrative, not because the single frame shows 18 months of change.
Inflamed or traumatized nevus

Why it fits: A dark papule can be a nevus that was irritated

Why not: The source says the nodule proved to be invasive melanoma

A benign irritated nevus is the mimic the source is overriding with its narrative, not with a visible timeline.
Thrombosed angioma or hemorrhage

Why it fits: Blue-black color can be blood

Why not: The source diagnosis is melanoma

Blue-black color is not specific for thrombus.

Closest mimic

Inflamed or traumatized nevus

A dark papule with a brown edge can be an irritated nevus. The source narrative is what overrides that mimic, and the narrative is not a visible timeline.

Why not

Inflamed nevus — Irritation can darken a nevus, but this caption says the new nodule proved to be invasive melanoma. The photograph alone does not show that proof.
Hemorrhage or thrombosed angioma — Blue-black color fits blood as well as pigment. Nothing in the frame shows a glass-slide test or a resolving bruise. The source diagnosis is what argues against stopping at blood.

Reasoning

One dark papule with a brown edge is visible. The NCI narrative adds a family follow-up story and says the nodule proved to be invasive melanoma in a dysplastic nevus. That narrative is not a second photograph and does not say histopathology.

Pixels support a dark papule only, and that papule is the major visible clue. An earlier photograph is not in the file, so a change you cannot see gets conflicting weight. The 18-month story, the 3-mm size, and the diagnosis have weight as source text. Histopathology has none. The word proved in the narrative is not a pathology report.

Diagnostic trap

Teaching a before-and-after lesson from a file that contains only the later look, or upgrading 'proved' into a pathology report.

Mentor note

This is an evidence-weighting case. If you cannot point to the earlier photo, do not pretend it is on the page.

Take-home rule

Separate the frame from the follow-up story, and do not invent the confirmation method.

Management brief

Nodule with a dark plugged center (case-g18-16)

Teaching type: Reasoning case
Curriculum level: 4 · mimic
Skills: Crateriform center
Recorded diagnosis: Keratoacanthoma
Disease record: keratoacanthoma
Confirmation: source_dataset_diagnosis — The Commons description says the plate illustrates a keratoacanthoma in a section on clinical manifestations of epidermal neoplasms, from the AFIP Atlas of Tumor Pathology. It does not quote a microscopy report, so histopathology is not claimed even though the book is a tumor atlas.
Site: Skin, site not named on the source

Provenance

clinical · Public domain · Armed Forces Institute of Pathology

File: assets/media/cases/case-21-clinical.jpg

Source: Armed Forces Institute of Pathology Atlas of Tumor Pathology, via Wikimedia Commons

Armed Forces Institute of Pathology. Public domain.

Modification: other-described — Recompressed for web delivery and file metadata removed. No crop and no annotation. The source scan is already low resolution.

Observations

A round red nodule fills most of the frame.
The center is darker and looks plugged or crater-like.
The photograph is soft and low in detail. Fine vessels are not resolved.

Observation prompts

What shape is the center of the nodule?
Is the photograph sharp enough to name fine vessels?

Features, certainty, and weight

Clinical morphology, dermoscopic structure, and image context are separate. An image mark does not compete with a diagnostic structure.

Clinical morphology

Crater or plug in a red nodule — Probably present; Major clue

A crater is not specific for one keratinizing tumor and is not proof against a melanocytic nodule. Detail is limited.

Canonical pattern: crateriform-center. Educational role: Diagnostic structure. Case certainty and weight stay on this case.

Dermoscopic structure

Fine surface vessels — Not visible in this image; Weak

This file does not resolve fine vessels. Do not add them.

Canonical pattern: surface-vessels. Educational role: Diagnostic structure. Case certainty and weight stay on this case.

Case-specific observation

None stored on this case.

Context and image information

None stored on this case.

Differential

Keratoacanthoma

Why it fits: Crater-like dark center; AFIP plate label

Why not: No microscopy quote; Image detail is limited

The atlas label is keratoacanthoma. The shape is what you can check.
Nodular melanoma

Why it fits: A dark raised center can be a melanoma nodule

Why not: The plate label is keratoacanthoma

This is the melanoma trap. A dark center is not pigment until you can say so, and this file is too soft to map dermoscopic pigment.
Cutaneous squamous cell carcinoma

Why it fits: Keratinizing nodules overlap with keratoacanthoma

Why not: The plate says keratoacanthoma rather than squamous cell carcinoma

Many practices treat that overlap as a pathology question. This caption does not resolve it with a quote from a report.

Closest mimic

Nodular melanoma

A dark raised center can be a melanocytic nodule. This file is too soft to map dermoscopic pigment, and the plate label is not that diagnosis.

Why not

Nodular melanoma — A dark nodule is where nodular melanoma hides. This plate is labeled keratoacanthoma, and the dark center reads as a plug in a red rim rather than as an irregular brown plaque. The file is too soft to exclude melanoma by pattern alone.
Squamous cell carcinoma — Keratoacanthoma and squamous cell carcinoma overlap clinically. The atlas title chooses keratoacanthoma and does not quote a microscopy report, so the separation is the label plus the crater shape, not a Docutis pathology review.

Reasoning

A soft photograph shows a round red nodule with a dark center. The AFIP plate says keratoacanthoma and does not quote microscopy. It is the crateriform mimic in this pathway.

The crater shape is the major clue and is only probably resolved, because the photograph is soft. Fine vessels are not visible, so they get weak weight and must not be named. The diagnosis is the atlas label. Histopathology is not quoted, so it is not counted.

Diagnostic trap

Calling every dark nodule melanoma, or calling every crater a keratoacanthoma without reading the label's limits.

Mentor note

Low resolution was accepted because the crater is still the teaching point and better licensed crater images were not added as filler.

Take-home rule

A plugged center is a shape. Read the source label, and do not pretend a tumor atlas sentence is a slide review.

Management brief

Damaged thumbnail with dark debris (case-g18-12)

Teaching type: Expert-challenge case
Curriculum level: 5 · melanoma
Skills: Nail-unit damage, Evidence weighting
Recorded diagnosis: Melanoma of the thumb
Disease record: acral-melanoma
Confirmation: clinical_diagnosis — The Commons description states melanoma of the thumb of an 82-year-old woman. It does not name a clinician role, histopathology, or an acral-lentiginous subtype. The Docutis disease link is the existing acral melanoma record because that is the nearest condition page, not because the caption used that subtype. The exact age is the source sentence; the case record stores only an older-adult band.
Site: Thumb nail unit

Provenance

clinical · CC BY 4.0 · Wawjak

File: assets/media/cases/case-17-clinical.jpg

Source: Wawjak, via Wikimedia Commons

Wawjak. CC BY 4.0. Via Wikimedia Commons.

Modification: other-described — Resized and recompressed for web delivery (max width 1400 px) and file metadata removed. No crop and no annotation.

Observations

The thumbnail plate is largely destroyed or lifted.
Dark brown-black material and pale debris occupy the nail bed area.
A small red mark is on the skin just beyond the nail, and cloth is at the side of the finger.

Observation prompts

What has happened to the nail plate?
Can you point to a pigmented streak on the fold, or would that be a guess?

Features, certainty, and weight

Clinical morphology, dermoscopic structure, and image context are separate. An image mark does not compete with a diagnostic structure.

Clinical morphology

Destroyed nail plate with dark debris — Clearly visible; Major clue

Nail destruction is not specific for a melanocytic tumor.

Canonical pattern: nail-plate-destruction. Educational role: Diagnostic structure. Case certainty and weight stay on this case.
A clear pigmented streak on the nail fold — Not visible in this image; Weak

A fold streak is not claimed from this frame. Do not supply one.

Canonical pattern: pigmented-nail-streak. Educational role: Diagnostic structure. Case certainty and weight stay on this case.

Dermoscopic structure

None stored on this case.

Case-specific observation

None stored on this case.

Context and image information

None stored on this case.

Differential

Melanoma of the thumb

Why it fits: Destroyed nail with dark debris; Source statement of thumb melanoma

Why not: No histopathology; No stated clinician role

The source diagnosis is used as a clinical label. It is the weakest confirmation method in this academy.
Nail-unit squamous cell carcinoma or other keratinocyte tumor

Why it fits: Nail destruction can be a keratinocyte tumor

Why not: The source text says melanoma

Nail destruction is not specific for a melanocytic tumor.
Trauma with hematoma and nail dystrophy

Why it fits: Blood and a broken nail follow injury

Why not: No injury history is written on the page; The source diagnosis is melanoma

Do not invent trauma to explain dark nail debris.

Closest mimic

Nail-unit squamous cell carcinoma or other keratinocyte tumor

Nail destruction is shared with keratinocyte tumors and with injury. The source line is a clinical label, which is the weakest confirmation method in this pathway.

Why not

Subungual hematoma from trauma — Blood under a nail is common and can look black. This frame shows plate destruction and debris rather than a discrete pool of blood with an intact plate, and the source calls it melanoma. A trauma history is not in the caption.
Nail-unit squamous cell carcinoma — Squamous cell carcinoma destroys nails and can bleed. The source text says melanoma and does not discuss keratinocyte carcinoma. Destruction alone cannot separate them, which is why this label is weak without pathology.

Reasoning

The thumbnail is destroyed, with dark and pale debris. The Commons line says melanoma of the thumb in an older woman and cites neither histopathology nor a subtype. The acral melanoma record is only the nearest Docutis page.

Nail destruction is clearly visible and is the major clue. A pigmented fold streak is not claimed, so it stays not visible and weak: do not add it. Diagnostic weight is a one-line clinical label, which is lower than an expert-attributed or pathology-cited source. Subtype has no weight because it is not in the source.

Diagnostic trap

Diagnosing a stripe that is not there, or treating this uploader line as if it were a pathology report.

Mentor note

This is the advanced evidence case because the picture is dramatic and the confirmation is thin. Drama is not certainty.

Take-home rule

Nail destruction needs a differential. A short source line does not become histopathology.

Management brief

Five looks in one teaching plate (case-g21-01)

Teaching type: Teaching case
Curriculum level: 1 · mimic
Skills: Range of ordinary moles
Recorded diagnosis: Common acquired nevus
Disease record: melanocytic-nevus
Confirmation: source_dataset_diagnosis — The NCI caption calls this the natural history of common acquired nevi and says the panels are ordinary moles, from a small macule to a pale papule. The same caption assigns junctional, compound, and dermal names. This file has no histopathology image, so those histologic words are not re-verified and are not used as the case method.
Site: Skin, site not named on the source

Provenance

clinical · Public domain · National Cancer Institute

File: assets/media/cases/case-22-clinical.jpg

Source: National Cancer Institute, via Wikimedia Commons

National Cancer Institute. Public domain.

Modification: other-described — Recompressed for web delivery and file metadata removed. No crop and no annotation. The longest edge was limited to 1600 pixels.

Observations

The file is a plate of five separate photographs, not one lesion.
Some panels are small brown spots. One panel is a dark raised papule. One panel is a pale pink papule.

Observation prompts

How many separate photographs are in the file?
Which panel is a dark raised spot, and which is pale?

Features, certainty, and weight

Clinical morphology, dermoscopic structure, and image context are separate. An image mark does not compete with a diagnostic structure.

Clinical morphology

Small brown macules — Clearly visible; Major clue

Small brown macules are in this plate. Size and a brown color do not prove a benign outcome.

Canonical pattern: small-brown-macule. Educational role: Descriptive morphology, not a dermoscopic structure. Case certainty and weight stay on this case.
Dark raised papule in one panel — Clearly visible; Supportive

One panel is a solitary dark papule. It does not inherit a benign reading from the other panels.

Canonical pattern: solitary-dark-papule. Educational role: Descriptive morphology, not a dermoscopic structure. Case certainty and weight stay on this case.

Dermoscopic structure

None stored on this case.

Case-specific observation

Pale papule in one panel — Clearly visible; Weak

The pale panel is not a pale center inside a darker rim.

Canonical pattern: not linked. One panel is a pale papule. It is not a pale center inside a darker rim, so it is not that pattern.

Context and image information

None stored on this case.

Differential

Common acquired nevus

Why it fits: The source caption names ordinary moles and shows more than one look

Why not: No histopathology image is in the file

The plate is the source's range of ordinary moles. It is not one patient's history.
Invasive melanoma arising in a dysplastic nevus

Why it fits: One panel is a solitary dark papule

Why not: The other panels are small brown spots and a pale papule, and the caption is not that melanoma label

One dark panel can resemble a melanoma photograph. The rest of the plate is not that case.

Closest mimic

Invasive melanoma arising in a dysplastic nevus

One panel is a solitary dark papule. That is the look of the library case with that recorded diagnosis. The other panels are not that lesion.

Why not

None recorded on this case.

Reasoning

The NCI plate is a range of ordinary-mole looks, including a dark papule and a pale papule. The caption's histologic names are not a slide in this file.

The small brown macules carry the major weight for what the caption is illustrating. The dark papule is supportive of the trap, not proof of a second diagnosis. The pale papule is a weak extra look. None of these weights is a probability.

Diagnostic trap

Treating the calmest panel as proof that the dark panel is harmless.

Mentor note

This is a composite plate. Sites are not named. Do not turn five photographs into one patient's story.

Take-home rule

A benign source label on a plate is not a guarantee for every panel, and not a guarantee for the next lesion you see.

Management brief

No management category is stored. A source label, including a benign label, is not a decision to reassure, monitor, perform dermoscopy, biopsy, or refer. This brief is not a protocol and remains review required.

Rough brown papule (case-g21-02)

Teaching type: Teaching case
Curriculum level: 2 · mimic
Skills: Stuck-on rough surface
Recorded diagnosis: Seborrheic keratosis
Disease record: seborrheic-keratosis
Confirmation: clinical_diagnosis — The Commons description says seborrheic keratosis close-up. It does not state histopathology or name a body site.
Site: Skin, site not named on the source

Provenance

clinical · CC BY-SA 4.0 · Assafn

File: assets/media/cases/case-23-clinical.jpg

Source: Assafn, via Wikimedia Commons

Assafn, via Wikimedia Commons. CC BY-SA 4.0.

Modification: other-described — Recompressed for web delivery and file metadata removed. No crop and no annotation.

Observations

A single brown oval lesion sits on otherwise even skin.
The surface is rough, with lighter tan and darker brown areas, and the edge looks as if the lesion sits on the skin.

Observation prompts

Is the surface smooth or rough?
Does the edge look as if it sits on the skin?

Features, certainty, and weight

Clinical morphology, dermoscopic structure, and image context are separate. An image mark does not compete with a diagnostic structure.

Clinical morphology

Rough stuck-on surface — Clearly visible; Major clue

A rough surface that looks stuck on is a clue. It is not proof of a benign lesion.

Canonical pattern: stuck-on-rough-surface. Educational role: Diagnostic structure. Case certainty and weight stay on this case.
More than one brown color — Clearly visible; Supportive

Tan and darker brown are both visible. Shared color is not a diagnosis.

Canonical pattern: color-variegation. Educational role: Diagnostic structure. Case certainty and weight stay on this case.

Dermoscopic structure

None stored on this case.

Case-specific observation

None stored on this case.

Context and image information

None stored on this case.

Differential

Seborrheic keratosis

Why it fits: Rough surface; Edge that looks stuck on the skin; Uploader label

Why not: No histopathology is stated

The label matches the stuck-on rough surface. The label is still a clinical caption.
Cutaneous melanoma

Why it fits: More than one brown color; An outline that is not a perfect oval

Why not: The surface is rough and stuck-on rather than a flat dark macule in this frame

Shared color is not the whole reading. The rough surface is the point of the comparison.

Closest mimic

Cutaneous melanoma

More than one brown color and an uneven outline are the looks already used on cutaneous melanoma cases in this library. This frame adds a rough stuck-on surface those frames do not show.

Why not

None recorded on this case.

Reasoning

The caption says seborrheic keratosis. The frame shows a rough brown papule with more than one brown color. Color overlap with melanoma cases is real. The rough surface is what this frame adds.

The rough stuck-on surface is the major clue. The second brown color is supportive and is also seen on melanoma cases, so it does not settle the reading. No histology is in the caption.

Diagnostic trap

Stopping at the first familiar benign name because the colors look like a melanoma photograph, or the reverse: ignoring a rough surface because the colors worry you.

Mentor note

The uploader did not name a site and did not cite a pathology report. Do not add either.

Take-home rule

Describe the surface. A benign caption does not make the next rough brown lesion safe.

Management brief

Ridged surface under a dermatoscope (case-g21-03)

Teaching type: Teaching case
Curriculum level: 2 · mimic
Skills: Ridged surface
Recorded diagnosis: Seborrheic keratosis
Disease record: seborrheic-keratosis
Confirmation: clinical_diagnosis — The author states that this polarized dermoscopic image shows a seborrheic keratosis. No histopathology report is attached. The method stays clinical_diagnosis rather than histopathology.
Site: Not specified; dermoscopic close-up

Provenance

dermoscopy · CC BY-SA 4.0 · Philipp Tschandl

File: assets/media/cases/case-24-dermoscopy.jpg

Source: Philipp Tschandl, via Wikimedia Commons

Philipp Tschandl, via Wikimedia Commons. CC BY-SA 4.0.

Modification: other-described — Recompressed for web delivery and file metadata removed. No crop and no annotation.

Observations

A yellow-tan oval lesion has a surface broken into ridges.
A millimeter scale lies beside the lesion. A few hairs cross the field.

Observation prompts

Is the surface smooth or broken into ridges?
What is printed beside the lesion, and is it skin?

Features, certainty, and weight

Clinical morphology, dermoscopic structure, and image context are separate. An image mark does not compete with a diagnostic structure.

Clinical morphology

None stored on this case.

Dermoscopic structure

Cerebriform ridges — Clearly visible; Major clue

A ridged surface is a dermoscopic clue. It is not proof of a benign lesion and it is not a count of pits.

Canonical pattern: cerebriform-surface. Educational role: Diagnostic structure. Case certainty and weight stay on this case.

Case-specific observation

None stored on this case.

Context and image information

Millimeter scale in the frame — Clearly visible; Weak

The scale is print. It is not skin and it is not a recorded measurement.

Canonical pattern: measuring-scale-in-frame. Educational role: Image mark, not a skin finding. Case certainty and weight stay on this case.

Differential

Seborrheic keratosis

Why it fits: Ridged yellow-tan surface; Author caption on a dermoscopic image

Why not: No histopathology is attached

The ridges are why this frame is in the library. The caption is still not a pathology report.
Cutaneous melanoma

Why it fits: A pigmented lesion can be the worry before the surface is described

Why not: This frame's surface is ridged and yellow-tan rather than a structureless dark blotch

Do not import a melanoma reading from another case before you describe these ridges.

Closest mimic

Cutaneous melanoma

A pigmented dermoscopic lesion is compared with cutaneous melanoma before the surface is described. This frame's ridges are the difference you can see.

Why not

None recorded on this case.

Reasoning

The author calls this a seborrheic keratosis under polarized dermoscopy. The ridges are visible. The scale is not a finding. Pits and cysts were not added.

The ridges carry the major weight. The scale is weak because it is not skin. No vessel pattern and no milia-like cyst were encoded.

Diagnostic trap

Reading the millimeter scale as a skin structure, or naming pits you have not separated from the ridges.

Mentor note

The file is 600 pixels on the long edge. The ridges are still readable. It was not enlarged.

Take-home rule

Describe ridges before you borrow a diagnosis from a different pigmented photograph. A benign caption is not a guarantee.

Management brief

Many brown spots on the back of a hand (case-g21-04)

Teaching type: Teaching case
Curriculum level: 2 · mimic
Skills: Many flat brown macules
Recorded diagnosis: Solar lentigo
Disease record: solar-lentigo
Confirmation: clinical_diagnosis — The French caption says lentigo sénile on the dorsum of the hand. Solar lentigo is the English name used for that caption. Histopathology is not stated. The photograph cannot clear every macule.
Site: Dorsum of the hand

Provenance

clinical · CC BY-SA 4.0 · Alain Gérard

File: assets/media/cases/case-25-clinical.jpg

Source: Alain Gérard, via Wikimedia Commons

Alain Gérard, via Wikimedia Commons. CC BY-SA 4.0.

Modification: other-described — Recompressed for web delivery and file metadata removed. No crop and no annotation.

Observations

Many separate brown macules sit on the back of a hand and the wrist.
The macules are not one broad patch. Some are small and some are larger. The borders are not all the same.

Observation prompts

Is this one brown patch or many separate spots?
What body site can you actually see?

Features, certainty, and weight

Clinical morphology, dermoscopic structure, and image context are separate. An image mark does not compete with a diagnostic structure.

Clinical morphology

Many flat brown macules — Clearly visible; Major clue

A field of flat brown macules is not one broad patch, and it is not proof that every macule is benign.

Canonical pattern: flat-brown-macule. Educational role: Descriptive morphology, not a dermoscopic structure. Case certainty and weight stay on this case.

Dermoscopic structure

None stored on this case.

Case-specific observation

None stored on this case.

Context and image information

None stored on this case.

Differential

Solar lentigo

Why it fits: Many flat brown macules on the dorsum of the hand; Caption says lentigo sénile

Why not: No histopathology; Not every macule has the same border

The caption names the field. It does not certify each spot.
Lentigo maligna melanoma

Why it fits: Brown pigment on sun-exposed skin

Why not: This frame is many hand macules, not one cheek patch marked for biopsy

Do not use a hand field to dismiss a single facial patch, or the reverse.
Cutaneous melanoma

Why it fits: Brown pigment can be uneven

Why not: This frame is a field of macules, not one broad patch

The library's broad brown melanoma photograph is a different shape.

Closest mimic

Lentigo maligna melanoma

Both are brown pigment on sun-exposed skin. This frame is many macules on a hand. The lentigo maligna melanoma case is one cheek patch.

Why not

None recorded on this case.

Reasoning

The caption says lentigo sénile on the dorsum of the hand. The frame shows many flat brown macules, not one patch. That does not clear every spot.

The field of flat brown macules is the major clue and matches the caption's site. Uneven borders on some macules are not given a second diagnosis from this photograph.

Diagnostic trap

Calling every brown spot on the hand harmless, or calling this field the same thing as one broad patch.

Mentor note

Nail polish and a watch are in the frame. They are not skin findings. No face is shown.

Take-home rule

Many flat brown macules on the hand are not a promise about the next single brown patch.

Management brief

Two bright red papules (case-g21-05)

Teaching type: Teaching case
Curriculum level: 2 · mimic
Skills: Bright red papule
Recorded diagnosis: Cherry angioma
Disease record: cherry-angioma
Confirmation: clinical_diagnosis — The Commons description says cherry angioma close-up. It does not name a site and does not state histopathology. Two papules are in the frame.
Site: Skin, site not named on the source

Provenance

clinical · CC BY-SA 4.0 · Assafn

File: assets/media/cases/case-26-clinical.jpg

Source: Assafn, via Wikimedia Commons

Assafn, via Wikimedia Commons. CC BY-SA 4.0.

Modification: other-described — Recompressed for web delivery and file metadata removed. No crop and no annotation.

Observations

Two bright red papules sit on otherwise even skin.
They are a similar vivid red. No brown pigment is visible in them. The site is not named.

Observation prompts

How many red spots are in the frame?
Are they the same color as each other?

Features, certainty, and weight

Clinical morphology, dermoscopic structure, and image context are separate. An image mark does not compete with a diagnostic structure.

Clinical morphology

Bright red papules — Clearly visible; Major clue

Bright red papules are a color finding. A second papule does not prove either one is benign.

Canonical pattern: bright-red-papule. Educational role: Descriptive morphology, not a dermoscopic structure. Case certainty and weight stay on this case.

Dermoscopic structure

None stored on this case.

Case-specific observation

None stored on this case.

Context and image information

None stored on this case.

Differential

Cherry angioma

Why it fits: Bright red papules; A second similar papule; Uploader label

Why not: No dermoscopy and no histopathology

The caption matches the color. Two papules still do not prove both are benign forever.
Basal cell carcinoma

Why it fits: A red papule is also the look of a shiny red papule case in this library

Why not: This frame has two vivid red papules, not one shiny papule with a named site

Do not call every red papule an angioma or every red papule a carcinoma.
Amelanotic melanoma

Why it fits: A red papule without brown pigment can be a melanocytic trap

Why not: A second matching bright red papule is in this same frame

Absence of brown pigment is not a reassuring test.

Closest mimic

Basal cell carcinoma

The library's solitary shiny red papule is a basal cell carcinoma. This frame is bright red and there are two papules.

Why not

None recorded on this case.

Reasoning

The caption says cherry angioma. Two bright red papules are visible. That is not the solitary shiny red papule of the basal cell carcinoma case, and it is not a proof.

The bright red color and the second papule are the major clue. No vessel pattern was encoded. No site was stored because the caption does not name one.

Diagnostic trap

Calling every red papule an angioma, or calling every red papule a carcinoma.

Mentor note

A different cherry angioma file on Commons carried location metadata and was not used. This close-up does not.

Take-home rule

A bright red papule can be benign in the caption and still not be a rule for the next red papule.

Management brief

Small blue spot under hair (case-g21-06)

Teaching type: Reasoning case
Curriculum level: 3 · mimic
Skills: Blue color
Recorded diagnosis: Blue nevus
Disease record: blue-nevus
Confirmation: clinical_diagnosis — The Commons description says a blue nevus on the shin. It does not state a histologic subtype and does not cite histopathology. Hairs cross the spot, so the full border is not traced.
Site: Shin

Provenance

clinical · CC0 1.0 · Nictitate

File: assets/media/cases/case-27-clinical.jpg

Source: Nictitate, via Wikimedia Commons

Nictitate, via Wikimedia Commons. CC0 1.0.

Modification: other-described — Recompressed for web delivery and file metadata removed. No crop and no annotation. The longest edge was limited to 1600 pixels.

Observations

A small blue spot sits on the skin.
Terminal hairs cross the spot, so part of the edge is hidden. No flat brown companion lesion is in the frame.

Observation prompts

What color is the small spot?
Do hairs hide any of its edge?

Features, certainty, and weight

Clinical morphology, dermoscopic structure, and image context are separate. An image mark does not compete with a diagnostic structure.

Clinical morphology

Blue papule or macule — Clearly visible; Major clue

Blue color is visible. It does not prove the source label and it does not name a subtype.

Canonical pattern: blue-papule. Educational role: Descriptive morphology, not a dermoscopic structure. Case certainty and weight stay on this case.

Dermoscopic structure

None stored on this case.

Case-specific observation

Hairs crossing the spot — Clearly visible; Weak

Hair hides part of the edge. It is not a skin structure.

Canonical pattern: not linked. Hairs cross the spot and hide part of the edge. Occlusion is not a reusable skin pattern.

Context and image information

None stored on this case.

Differential

Blue nevus

Why it fits: Blue color; Caption names the shin

Why not: No histopathology; Border partly hidden by hair

The caption is a clinical label for a blue spot. It does not assign a histologic subtype.
Superficial spreading melanoma arising from a dysplastic nevus

Why it fits: That library case has a blue-black raised area

Why not: That case also has a flatter area and a printed arrow. This frame does not.

Blue-black color is shared as a worry. The companion flat area is not in this frame.

Closest mimic

Superficial spreading melanoma arising from a dysplastic nevus

That case records a blue-black raised area. This frame is a small blue spot without the flat companion seen there.

Why not

Superficial spreading melanoma arising from a dysplastic nevus — That case has a blue-black raised area beside a flatter area and a printed arrow. This frame has no flat companion and no arrow.
Pigmented basal cell carcinoma — No leaf-like or ovoid structure is visible here. Blue color alone does not make that diagnosis.

Reasoning

The caption says blue nevus on the shin. The spot is blue and partly covered by hair. No subtype was added.

Blue color is the major clue and is not specific. Hair is weak because it is occlusion. The missing flat companion is a difference from the melanoma case, not a proof.

Diagnostic trap

Treating blue color as a benign diagnosis, or as a melanoma diagnosis, without the rest of the frame.

Mentor note

A second blue-nevus file was rejected because marker streaks hid the border. This one still has hair across the spot. That limit stays in the note.

Take-home rule

Blue is a color. A benign caption for one blue spot is not a guarantee for the next blue-black lesion.

Management brief

A group of papules on the chest (case-g21-08)

Teaching type: Teaching case
Curriculum level: 3 · mimic
Skills: Grouped papules
Recorded diagnosis: Sebaceous hyperplasia
Disease record: sebaceous-hyperplasia
Confirmation: expert_diagnosis — The Commons description cites a 2014 case report that labels the photographs sebaceous gland hyperplasia in a linear group on the chest. The file description does not quote a histopathology sentence, so histopathology is not claimed. The journal statement reprinted on the file page is an unversioned attribution license; the file itself is tagged CC BY 4.0.
Site: Chest

Provenance

clinical · CC BY 4.0 · Toshitsugu Sato and Masaru Tanaka

File: assets/media/cases/case-29-clinical.jpg

Source: Sato and Tanaka, Dermatology Practical & Conceptual (2014), via Wikimedia Commons

Sato T, Tanaka M. Dermatology Practical & Conceptual. 2014. Via Wikimedia Commons. CC BY 4.0.

Modification: other-described — Recompressed for web delivery and file metadata removed. No crop and no annotation.
dermoscopy · CC BY 4.0 · Toshitsugu Sato and Masaru Tanaka

File: assets/media/cases/case-29-dermoscopy.jpg

Source: Sato and Tanaka, Dermatology Practical & Conceptual (2014), via Wikimedia Commons

Sato T, Tanaka M. Dermatology Practical & Conceptual. 2014. Via Wikimedia Commons. CC BY 4.0.

Modification: other-described — Recompressed for web delivery and file metadata removed. No crop and no annotation.

Observations

A group of skin-colored papules sits on the chest in a loose line. A nipple is at the edge of the clinical frame.
The dermoscopic frame shows clustered yellow-white lobules. A gel bubble is at the edge.

Observation prompts

Are the bumps one lesion or a group?
On the close view, are the bumps smooth or lobulated?

Features, certainty, and weight

Clinical morphology, dermoscopic structure, and image context are separate. An image mark does not compete with a diagnostic structure.

Clinical morphology

Grouped skin-colored papules — Clearly visible; Major clue

A group of skin-colored papules is this clinical frame. It is not proof of a benign lesion.

Canonical pattern: grouped-skin-colored-papules. Educational role: Descriptive morphology, not a dermoscopic structure. Case certainty and weight stay on this case.

Dermoscopic structure

Yellow-white lobules — Clearly visible; Major clue

Lobules are visible on the dermoscopic frame. Vessels were not counted.

Canonical pattern: yellow-white-lobules. Educational role: Diagnostic structure. Case certainty and weight stay on this case.

Case-specific observation

None stored on this case.

Context and image information

None stored on this case.

Differential

Sebaceous hyperplasia

Why it fits: Grouped skin-colored papules; Yellow-white lobules; Case-report label and chest site

Why not: Histopathology is not quoted from the file page

The paper label matches these frames. The linear arrangement is this case, not a rule for every papule.
Basal cell carcinoma

Why it fits: Small papules can raise that question; A solitary shiny red papule is a different library case

Why not: This clinical frame is a group of skin-colored papules, not one shiny red papule

Number and color differ from the solitary shiny red papule. That is not a proof.
Molluscum contagiosum

Why it fits: Grouped papules can look similar at a glance

Why not: The dermoscopic frame shows yellow-white lobules rather than a single central plug you can point to

Do not rename lobules as a plug.

Closest mimic

Basal cell carcinoma

Small papules raise that comparison. The basal cell carcinoma case in the pair is one shiny red papule. This frame is a skin-colored group.

Why not

None recorded on this case.

Reasoning

The case report labels these chest photographs sebaceous hyperplasia. The clinical frame is a group of papules. The dermoscopic frame shows yellow-white lobules. Vessels were left uncounted.

Both the group and the lobules are major and clearly visible. Vessels stay out of the pattern list. The linear distribution is the paper's description of this case, not a required shape.

Diagnostic trap

Calling every grouped papule this diagnosis, or calling every papule a carcinoma because another case is a red papule.

Mentor note

The Commons tag is CC BY 4.0. The reprinted journal sentence does not name the version. That limit is recorded and the images were still used because the file page states CC BY 4.0.

Take-home rule

Grouped lobulated papules are a look. A benign case-report label is not a guarantee for the next papule.

Management brief

Brown patch with ink dots (case-g21-07)

Teaching type: Expert-challenge case
Curriculum level: 4 · melanoma
Skills: Marked cheek patch
Recorded diagnosis: Lentigo maligna melanoma
Disease record: lentigo-maligna-melanoma
Confirmation: expert_diagnosis — The caption says lentigo maligna melanoma of the left central malar cheek marked for biopsy. A histopathology report is not on the Commons page. The method stays expert_diagnosis, the same limit used for this uploader's other biopsy-marked caption in the library, and it is not histopathology.
Site: Left central malar cheek

Provenance

clinical · CC BY-SA 4.0 · Dermanonymous

File: assets/media/cases/case-28-clinical.jpg

Source: Dermanonymous, via Wikimedia Commons

Dermanonymous, via Wikimedia Commons. CC BY-SA 4.0.

Modification: other-described — Recompressed for web delivery and file metadata removed. No crop and no annotation.

Observations

One brown patch sits in a tight crop of skin.
Several small dark dots surround the patch. They look like marker ink, not a second lesion.

Observation prompts

Is the brown pigment one patch or many separate spots?
What are the small dark dots around it?

Features, certainty, and weight

Clinical morphology, dermoscopic structure, and image context are separate. An image mark does not compete with a diagnostic structure.

Clinical morphology

Brown patch — Probably present; Major clue

One brown patch is visible. Flatness is probable in this crop and is not a histologic level.

Canonical pattern: flat-brown-macule. Educational role: Descriptive morphology, not a dermoscopic structure. Case certainty and weight stay on this case.

Dermoscopic structure

None stored on this case.

Case-specific observation

None stored on this case.

Context and image information

Marker dots around the patch — Clearly visible; Conflicts with a simple reading

Ink is not a border and not a diagnosis.

Canonical pattern: marker-ink. Educational role: Image mark, not a skin finding. Case certainty and weight stay on this case.

Differential

Lentigo maligna melanoma

Why it fits: Caption names that diagnosis on the cheek; One brown patch

Why not: No histopathology result is linked; The image is small

Use the caption's words. Do not shorten them to in situ, and do not invent a subtype beyond the caption.
Solar lentigo

Why it fits: Flat brown pigment on sun-exposed skin

Why not: This frame is one cheek patch with ink, not a field of hand macules

The hand field and this cheek patch are different photographs.
Pigmented actinic keratosis

Why it fits: A brown patch on the cheek can raise that question

Why not: Scale and a rough surface are not what this frame shows

Do not add scale that is not visible.

Closest mimic

Solar lentigo

Both are brown pigment. The solar lentigo case is many macules on a hand. This frame is one cheek patch with marker ink.

Why not

Solar lentigo — The solar lentigo photograph is a field of macules on the dorsum of the hand. This is one cheek patch. The field does not answer for this patch.
Pigmented actinic keratosis — This frame does not show a rough scaly surface. That absence is not a proof, and scale was not invented.

Reasoning

The caption says lentigo maligna melanoma on the malar cheek, marked for biopsy. The image shows one brown patch and ink. It does not show a pathology result, and it is not a field of hand macules.

The brown patch is the major clue and is only probably a flat macule, because the crop does not prove height. Ink conflicts with any reading that treats the dots as skin. The diagnosis is the caption, not a slide.

Diagnostic trap

Using a hand full of brown spots to dismiss a single cheek patch, or shortening this caption to in situ.

Mentor note

The file is 426 by 318 pixels. It was kept because the patch and the ink are still readable, and a larger licensed lentigo maligna melanoma photograph was not substituted.

Take-home rule

Read the caption's full words. Ink is not skin, a biopsy mark is not a result, and a benign field elsewhere is not this lesion.

Management brief

Dark patch under a fingernail (case-g22-01)

Teaching type: Reasoning case
Curriculum level: 4 · mimic
Skills: Color under a nail
Recorded diagnosis: Subungual haemorrhage
Disease record: subungual-haemorrhage
Confirmation: clinical_diagnosis — The Commons description says this is a subungual hematoma of the finger. It does not cite histopathology, a clinician role, dermoscopy, or a trauma history. The spelling on the file is hematoma. Docutis uses haemorrhage as the teaching label and does not upgrade the method.
Site: Finger nail unit

Provenance

clinical · CC BY-SA 4.0 · Callaleo

File: assets/media/cases/case-30-clinical.jpg

Source: Callaleo, via Wikimedia Commons

Callaleo, via Wikimedia Commons. CC BY-SA 4.0.

Modification: other-described — The Commons file had already been cropped by a later editor. This copy was recompressed for web delivery, the longest edge was limited to 1600 pixels, and file metadata was removed. No further crop and no annotation.

Observations

One fingernail has a purple to blue-black patch under the nail plate. The free edge of that nail is still pale.
Other nails in the frame do not show the same patch. No scale, ink, or dermatoscope is in the frame.

Observation prompts

What color is under the nail?
Is the nail plate missing, or is the free edge still pale?

Features, certainty, and weight

Clinical morphology, dermoscopic structure, and image context are separate. An image mark does not compete with a diagnostic structure.

Clinical morphology

Destroyed nail plate — Not visible in this image; Conflicts with a simple reading

The plate and pale free edge are still in the frame. Destruction is not visible. Absence is not a proof.

Canonical pattern: nail-plate-destruction. Educational role: Diagnostic structure. Case certainty and weight stay on this case.

Dermoscopic structure

None stored on this case.

Case-specific observation

Purple patch under the nail — Clearly visible; Major clue

A purple patch is visible under the plate. It is not a longitudinal streak and it does not prove the caption.

Canonical pattern: not linked. A purple patch under an intact nail plate is not the destroyed-plate pattern and not a longitudinal streak. It stays case-specific rather than a new pattern id.

Context and image information

None stored on this case.

Differential

Subungual haemorrhage

Why it fits: Purple patch under the nail; Pale free edge still present; Caption names a hematoma of the finger

Why not: No trauma history is written; No histopathology

The caption is a clinical label for this finger. It does not clear the next dark nail.
Melanoma of the thumb

Why it fits: Both are nail-unit photographs with dark color

Why not: That case shows a destroyed nail plate. This plate is not missing.

Plate destruction is the visible difference in those two frames. It is not a proof.

Closest mimic

Melanoma of the thumb

That case is also a nail-unit photograph with dark material. Its plate is destroyed. This frame keeps a pale free edge.

Why not

Melanoma of the thumb — That photograph shows a destroyed nail plate with debris. This plate is still there, with a pale free edge. The difference does not prove either caption.
Nail-unit squamous cell carcinoma or other keratinocyte tumor — No mass and no destroyed plate are in this frame. That absence does not exclude a keratinocyte tumor, and this caption does not diagnose one.

Reasoning

The caption says a subungual hematoma of the finger. The photograph shows a purple patch under a nail whose free edge is still pale. It does not show a destroyed plate, a fold streak, or dermoscopy.

The patch is clearly visible and is the major clue. It is not specific. Plate destruction conflicts with treating this as the destroyed-plate photograph, and it stays not visible. The caption is a clinical label, which is a weak confirmation.

Diagnostic trap

Reading every dark nail as blood, or as melanoma, because another nail photograph was dramatic.

Mentor note

No dermoscopic partner with a compatible license was added. A clinical photograph was not relabeled as dermoscopy. A longitudinal streak was not inferred from the diagnosis.

Take-home rule

Color under a nail is a look. A benign caption for one finger is not a guarantee, and a destroyed plate in another case is a different frame.

Management brief

A light brown patch on the forehead (case-g24-01)

Teaching type: Expert-challenge case
Curriculum level: 4 · melanoma
Skills: Evidence weighting
Recorded diagnosis: Melanoma in situ
Disease record: cutaneous-melanoma
Confirmation: clinical_diagnosis — Both Commons descriptions, checked 2026-10-01, state melanoma in situ on the right forehead marked for biopsy. The dermatoscope file calls itself a dermatoscope image of that description. Neither description reports histopathology. Marked for biopsy is not a histology result. In situ is the file's own wording, not a Docutis upgrade, and it is not lentigo maligna unless the file had said that.
Site: Right forehead

Provenance

clinical · CC BY-SA 4.0 · Dermanonymous

File: assets/media/cases/case-31-clinical.jpg

Source: Dermanonymous, via Wikimedia Commons

Dermanonymous, via Wikimedia Commons. CC BY-SA 4.0.

Modification: other-described — Embedded metadata segments were removed. Pixel dimensions were not changed. No crop and no annotation.
dermoscopy · CC BY-SA 4.0 · Dermanonymous

File: assets/media/cases/case-31-dermoscopy.jpg

Source: Dermanonymous, via Wikimedia Commons

Dermanonymous, via Wikimedia Commons. CC BY-SA 4.0.

Modification: other-described — Embedded metadata segments were removed. Pixel dimensions were not changed. No crop and no annotation.

Observations

A light brown patch sits on lined forehead skin. Purple and black dots ring the patch.
The circular field shows a faint light-brown area. Purple ink sits at the edge, and short tick marks cross the center.

Observation prompts

What color is the patch, and where are the dots?
On the circular field, what is ink or a tick mark rather than the brown area?

Features, certainty, and weight

Clinical morphology, dermoscopic structure, and image context are separate. An image mark does not compete with a diagnostic structure.

Clinical morphology

Light brown patch — Clearly visible; Major clue

A light brown patch is on forehead skin. A trunk network word is not used. The patch is not proof of the source label.

Canonical pattern: flat-brown-macule. Educational role: Descriptive morphology, not a dermoscopic structure. Case certainty and weight stay on this case.

Dermoscopic structure

None stored on this case.

Case-specific observation

None stored on this case.

Context and image information

Marker dots around the patch — Clearly visible; Conflicts with a simple reading

Purple and black dots ring the clinical patch, and purple ink is at the edge of the circular field. Ink is not skin pigment.

Canonical pattern: marker-ink. Educational role: Image mark, not a skin finding. Case certainty and weight stay on this case.
Tick marks in the circular field — Clearly visible; Conflicts with a simple reading

Short tick marks cross the dermoscopic field. They are a scale, not a skin structure.

Canonical pattern: measuring-scale-in-frame. Educational role: Image mark, not a skin finding. Case certainty and weight stay on this case.

Differential

Melanoma in situ

Why it fits: The file description uses those words for this forehead patch.; The patch is a single light-brown area rather than a field of many macules.

Why not: No histopathology sentence is on the file page.; The dermoscopic frame does not show a structure clear enough to name.

The source label can be revealed later. The frames do not prove it, and they do not let you invent a subtype the file did not use.
Solar lentigo

Why it fits: A flat light-brown patch on facial skin can look like this.; The color is mostly one light brown.

Why not: The stored solar lentigo case is many macules on the hand, not this single forehead patch.; A benign name is not established by the photograph.

A faint facial patch is the usual mimic. The hand field does not answer for this forehead.
Pigmented actinic keratosis

Why it fits: Facial skin with a brown patch can raise that comparison.

Why not: Scale was not clearly seen and was not invented.

Missing scale does not exclude a keratinocyte patch, and it does not prove the source label.

Closest mimic

Solar lentigo

A flat light-brown patch on facial skin is the usual benign look. The stored lentigo photograph is many macules on the hand, not this single forehead patch.

Why not

Solar lentigo — A flat light-brown facial patch can be a solar lentigo. This frame is one patch, not the field of hand macules in the lentigo case. That difference does not prove either label.
Pigmented actinic keratosis — Facial pigment can be a keratinocyte patch. Scale was not clearly seen and was not invented. Absence of scale does not exclude it.

Reasoning

The Commons descriptions label these two frames melanoma in situ on the right forehead, marked for biopsy, and call the second a dermatoscope image. The clinical frame is a light brown patch with marker dots. The dermoscopic frame is a faint brown area with ink and tick marks. No histopathology is stated.

The patch is clearly visible and is the major clue. Ink and the scale are clearly visible and conflict if you read them as skin. The file label is a clinical description, which is weak confirmation. Histopathology has no weight because it is absent.

Diagnostic trap

Calling every faint forehead patch this diagnosis, or calling it harmless because the circular frame did not show a textbook structure.

Mentor note

The pair is the file descriptions, not merely the same author. Pixels were inspected. A pigment network, gray dots, and facial rhomboids were not clear and were not added. The cheek case stays a different lesion.

Take-home rule

A faint facial patch plus marker ink is a look. An equivocal dermoscopic frame does not prove or clear the source label.

Management brief

No management category is stored. A file description, including a melanoma term, is not a decision to reassure, monitor, perform dermoscopy, biopsy, or refer. This brief is not a protocol and remains review required.

A pink-brown patch on the back (case-g24-02)

Teaching type: Expert-challenge case
Curriculum level: 4 · melanoma
Skills: Color variegation, Evidence weighting
Recorded diagnosis: Malignant melanoma
Disease record: cutaneous-melanoma
Confirmation: clinical_diagnosis — Both Commons descriptions, checked 2026-10-01, state malignant melanoma, left mid back, marked for biopsy. The dermatoscope file adds that the view is through a dermatoscope. Neither description reports histopathology, a subtype, Breslow thickness, or a stage. Marked for biopsy is not histology.
Site: Left mid back

Provenance

clinical · CC BY-SA 4.0 · Dermanonymous

File: assets/media/cases/case-32-clinical.jpg

Source: Dermanonymous, via Wikimedia Commons

Dermanonymous, via Wikimedia Commons. CC BY-SA 4.0.

Modification: other-described — Embedded metadata segments were removed. Pixel dimensions were not changed. No crop and no annotation.
dermoscopy · CC BY-SA 4.0 · Dermanonymous

File: assets/media/cases/case-32-dermoscopy.jpg

Source: Dermanonymous, via Wikimedia Commons

Dermanonymous, via Wikimedia Commons. CC BY-SA 4.0.

Modification: other-described — Embedded metadata segments were removed. Pixel dimensions were not changed. No crop and no annotation.

Observations

A pink and brown patch sits on the skin. Black dots ring the patch.
The circular field is mostly pink, with a brown area toward one side. Purple ink is at the edge, and tick marks sit along the top.

Observation prompts

Which colors are in the patch?
Which marks are ink or ticks rather than skin?

Features, certainty, and weight

Clinical morphology, dermoscopic structure, and image context are separate. An image mark does not compete with a diagnostic structure.

Clinical morphology

None stored on this case.

Dermoscopic structure

None stored on this case.

Case-specific observation

Pink and brown in one patch — Clearly visible; Major clue

Pink and brown are both visible. That is not the stored pattern of more than one dark color, so this look stays case-specific.

Canonical pattern: not linked. Pink and brown are both visible in one patch. That is not the stored pattern of more than one dark color, so it stays case-specific rather than a new pattern id.

Context and image information

Marker dots around the patch — Clearly visible; Conflicts with a simple reading

Black dots ring the clinical patch, and purple ink is at the edge of the circular field. Ink is not a skin border.

Canonical pattern: marker-ink. Educational role: Image mark, not a skin finding. Case certainty and weight stay on this case.
Tick marks along the circular field — Clearly visible; Conflicts with a simple reading

Tick marks sit along the top of the dermoscopic field. They are a scale, not vessels and not a network.

Canonical pattern: measuring-scale-in-frame. Educational role: Image mark, not a skin finding. Case certainty and weight stay on this case.

Differential

Malignant melanoma

Why it fits: The file description uses those words for this back patch.; More than one color, pink and brown, is in the patch.

Why not: No histopathology sentence is on the file page.; The dermoscopic frame does not show a structure clear enough to name.

The source label is not a subtype, a thickness, or a stage. The frames do not add those.
Melanocytic nevus

Why it fits: A pink-brown patch can be a mole.

Why not: No regular network was clear enough to name, and one was not inferred from the label.

A mole remains possible on the look alone. The file label does not settle it.
Seborrheic keratosis

Why it fits: Brown color also appears in the stuck-on keratosis photograph.

Why not: This frame does not show a rough stuck-on plate or dermoscopic ridges.

Shared brown color is not the keratosis surface. Missing ridges do not prove the source label.

Closest mimic

Melanocytic nevus

A pink-brown patch can be a mole. No network was clear on the circular frame, and a network was not inferred.

Why not

Melanocytic nevus — A pink-brown patch can be a mole. No network was clear enough to name. That absence does not prove a mole and does not prove the file label.
Seborrheic keratosis — The keratosis photograph has a rough stuck-on surface. This patch does not. Missing that surface does not prove either caption.

Reasoning

The Commons descriptions label these two frames malignant melanoma on the left mid back, marked for biopsy, and say the second is through a dermatoscope. The clinical frame is a pink and brown patch with black dots. The dermoscopic frame is pink and brown with ink and tick marks. No subtype and no histopathology are stated.

Pink and brown are clearly visible and are the major clue. Ink and the scale are clearly visible and conflict if you read them as skin. The file label is a clinical description, which is weak confirmation. Histopathology has no weight because it is absent.

Diagnostic trap

Inventing a network or a vessel pattern because the file uses a melanoma term, or dismissing the patch because those structures were not clear.

Mentor note

The pair is the through-dermatoscope sentence plus the matching date, author, and site wording. Pixels were inspected. Structures that were not sharp were not added. The seborrheic keratosis photograph is a different case.

Take-home rule

Pink and brown plus marker ink are a look. An equivocal dermoscopic frame does not prove the file label and does not make the patch safe.

Management brief

A small brown macule on the thigh (case-g25-01)

Teaching type: Reasoning case
Curriculum level: 3 · melanoma
Skills: Pigment network, Evidence weighting
Recorded diagnosis: Melanoma in situ
Disease record: cutaneous-melanoma
Confirmation: histopathology — The Figure 2 caption of De Giorgi and coauthors (Cancers 2026, doi:10.3390/cancers18142183), checked 2026-10-02, labels panels A and B as Case 1 and states: Histopathology confirmed melanoma in situ. No subtype, Breslow thickness, or stage is given for this lesion, and none was added.
Site: Right thigh

Provenance

clinical · CC BY 4.0 · Vincenzo De Giorgi and coauthors

File: assets/media/cases/case-33-clinical.jpg

Source: De Giorgi V, Cecchi G, Marabini V, Gurioli G, Perillo G, Fazzari F, Zuccaro B, et al. Cancers 2026, via PubMed Central (PMC13406897)

De Giorgi and coauthors, Cancers 2026, Figure 2 panel A, doi:10.3390/cancers18142183. CC BY 4.0. Cropped from the composite figure by Docutis.

Modification: cropped — Panel A of Figure 2 was cropped from the PMC figure file cancers-18-02183-g002.jpg (PMC open-access package PMC13406897.1), source sha256 7c4b404f062fccda702d716a8312c3335af1c88158c7def83ff9d0128608f942, at pixel box left 0, top 0, right 361, bottom 268 with Pillow, then saved as JPEG quality 90 without metadata. Output sha256 20bca7e242ef77be6e22a617900f047e7efae449bf75105895b14c4567e1e38c. No color change, no annotation, and no other edit.
dermoscopy · CC BY 4.0 · Vincenzo De Giorgi and coauthors

File: assets/media/cases/case-33-dermoscopy.jpg

Source: De Giorgi V, Cecchi G, Marabini V, Gurioli G, Perillo G, Fazzari F, Zuccaro B, et al. Cancers 2026, via PubMed Central (PMC13406897)

De Giorgi and coauthors, Cancers 2026, Figure 2 panel B, doi:10.3390/cancers18142183. CC BY 4.0. Cropped from the composite figure by Docutis.

Modification: cropped — Panel B of Figure 2 was cropped from the PMC figure file cancers-18-02183-g002.jpg (PMC open-access package PMC13406897.1), source sha256 7c4b404f062fccda702d716a8312c3335af1c88158c7def83ff9d0128608f942, at pixel box left 363, top 0, right 723, bottom 268 with Pillow, then saved as JPEG quality 90 without metadata. Output sha256 1e2091ed0c5d825d8b3dfa675ec932fd77ed9d8c491d7b54e4aa3040ad3704a3. No color change, no annotation, and no other edit.

Observations

A small brown macule with a darker center and a lighter brown rim sits beside a ruler. A small lighter lobe touches one edge.
A net of brown lines covers most of the lesion. The lines are thicker and darker in the center and fainter toward the edge. A few small dark dots sit in the darker center. A separate brown lobe sits at one side, and tick marks lie along the edge of the field.

Observation prompts

Is the brown net the same in every part of the lesion?
Which marks are scale ticks rather than skin?

Features, certainty, and weight

Clinical morphology, dermoscopic structure, and image context are separate. An image mark does not compete with a diagnostic structure.

Clinical morphology

Two browns and an uneven outline — Clearly visible; Supportive

The clinical macule has a darker center, a lighter rim, and a small side lobe. This is a look, not a structure.

Canonical pattern: irregular-brown-patch. Educational role: Descriptive morphology, not a dermoscopic structure. Case certainty and weight stay on this case.

Dermoscopic structure

Uneven brown net — Clearly visible; Major clue

Thicker, darker central lines and fainter edge lines are visible in the frame. The source caption calls the network atypical. The same look appears on a benign case in the same figure.

Canonical pattern: atypical-pigment-network. Educational role: Diagnostic structure. Case certainty and weight stay on this case.

Case-specific observation

A few small dark central dots — Probably present; Supportive

A few small dark dots sit in the darker center. They are too few and small to anchor a reusable dots-and-globules pattern from this frame.

Canonical pattern: not linked. A few small dark dots are probable in one frame. A reusable dots-and-globules pattern is deferred until a clearer example exists, rather than created from one weak example.

Context and image information

Ruler and tick marks — Clearly visible; Conflicts with a simple reading

A ruler sits beside the clinical macule and tick marks lie along the dermoscopic field. They are scales, not skin.

Canonical pattern: measuring-scale-in-frame. Educational role: Image mark, not a skin finding. Case certainty and weight stay on this case.

Differential

Melanoma in situ

Why it fits: The net is uneven across the lesion.; A few dark dots sit in the darker center.; The figure caption reports histopathology for this lesion.

Why not: The lesion is small.; No blue-white or vessel structure is visible.

The caption's histopathology sentence is the confirmation. The frames justify concern; they do not confirm.
Melanocytic nevus with cytologic atypia

Why it fits: A nevus with cytologic atypia in the same source figure shows a similar uneven net.

Why not: The caption gives a different histopathology result for this lesion.

Dermoscopy did not separate this lesion from the nevus in the same figure. Histopathology did.
Solar lentigo

Why it fits: Flat brown pigment.

Why not: The pigment forms a net of lines, not an even brown area with a moth-eaten edge.

A net of uneven lines is a melanocytic look. A lentigo is not the closest mimic here.

Closest mimic

Melanocytic nevus with cytologic atypia

A histopathology-confirmed nevus with cytologic atypia in the same source figure shows a similar uneven net.

Why not

Melanocytic nevus with cytologic atypia — A nevus in the same figure shows a similar uneven net. Its caption gives a different histopathology result. The frames alone do not separate them.
Solar lentigo — The pigment forms a net of lines, not an even brown area. A lentigo is not the closest look here.

Reasoning

The source labels these two frames as one case and states that histopathology confirmed melanoma in situ. The clinical frame shows a small brown macule with two browns. The dermoscopic frame shows an uneven brown net with a few dark central dots.

The uneven net is clearly visible and is the major clue. The dark dots are probably visible and supportive. The uneven clinical outline is supportive. The ruler and ticks conflict only if read as skin. The histopathology sentence is the confirmation; the dermoscopic look alone did not separate this lesion from a nevus in the same figure.

Diagnostic trap

Treating an atypical net as a diagnosis, or treating a small diameter as reassurance.

Mentor note

The source figure holds this case and a nevus with cytologic atypia side by side. Both show an uneven net. Use them together: dermoscopy justified excision of both, and histopathology separated them.

Take-home rule

An uneven net on a small macule is a reason for concern and a reason for histopathology. It is not the diagnosis.

Management brief

No management category is stored. The source reports excision and histopathology; that history is not a Docutis recommendation. This brief is not a protocol and remains review required.

A dark brown macule on the lower leg (case-g25-02)

Teaching type: Reasoning case
Curriculum level: 4 · mimic
Skills: Pigment network
Recorded diagnosis: Lentiginous melanocytic nevus with cytologic atypia
Disease record: melanocytic-nevus
Confirmation: histopathology — The Figure 2 caption of De Giorgi and coauthors (Cancers 2026, doi:10.3390/cancers18142183), checked 2026-10-02, labels panels C and D as Case 2 and states: Histopathology confirmed a lentiginous melanocytic nevus with cytologic atypia. The source term was kept. No grade beyond that wording was added.
Site: Right lower leg

Provenance

clinical · CC BY 4.0 · Vincenzo De Giorgi and coauthors

File: assets/media/cases/case-34-clinical.jpg

Source: De Giorgi V, Cecchi G, Marabini V, Gurioli G, Perillo G, Fazzari F, Zuccaro B, et al. Cancers 2026, via PubMed Central (PMC13406897)

De Giorgi and coauthors, Cancers 2026, Figure 2 panel C, doi:10.3390/cancers18142183. CC BY 4.0. Cropped from the composite figure by Docutis.

Modification: cropped — Panel C of Figure 2 was cropped from the PMC figure file cancers-18-02183-g002.jpg (PMC open-access package PMC13406897.1), source sha256 7c4b404f062fccda702d716a8312c3335af1c88158c7def83ff9d0128608f942, at pixel box left 0, top 270, right 361, bottom 538 with Pillow, then saved as JPEG quality 90 without metadata. Output sha256 3cb08364c5e0eb24b16ec701ed82676974ee93e0bb661339ef05bfa09610d34a. No color change, no annotation, and no other edit.
dermoscopy · CC BY 4.0 · Vincenzo De Giorgi and coauthors

File: assets/media/cases/case-34-dermoscopy.jpg

Source: De Giorgi V, Cecchi G, Marabini V, Gurioli G, Perillo G, Fazzari F, Zuccaro B, et al. Cancers 2026, via PubMed Central (PMC13406897)

De Giorgi and coauthors, Cancers 2026, Figure 2 panel D, doi:10.3390/cancers18142183. CC BY 4.0. Cropped from the composite figure by Docutis.

Modification: cropped — Panel D of Figure 2 was cropped from the PMC figure file cancers-18-02183-g002.jpg (PMC open-access package PMC13406897.1), source sha256 7c4b404f062fccda702d716a8312c3335af1c88158c7def83ff9d0128608f942, at pixel box left 363, top 270, right 723, bottom 538 with Pillow, then saved as JPEG quality 90 without metadata. Output sha256 781637b095f84a09fef8566498537db9493d43d0193c888ee6654af3cc8f0af0. No color change, no annotation, and no other edit.

Observations

A small dark brown macule with an uneven outline sits on hair-bearing skin beside a ruler.
A net of brown lines covers an irregular brown area. The lines are darker and thicker toward the center. Round clear air bubbles, hairs, and black tick marks cross the field.

Observation prompts

Where is the net darkest and thickest?
Which round shapes are air bubbles rather than skin structures?

Features, certainty, and weight

Clinical morphology, dermoscopic structure, and image context are separate. An image mark does not compete with a diagnostic structure.

Clinical morphology

None stored on this case.

Dermoscopic structure

Uneven brown net — Clearly visible; Major clue

The net is darker and thicker toward the center and fainter at the edge. The source caption calls it atypical. The same look appears on a melanoma in situ in the same figure.

Canonical pattern: atypical-pigment-network. Educational role: Diagnostic structure. Case certainty and weight stay on this case.

Case-specific observation

Air bubbles and hairs in the field — Clearly visible; Conflicts with a simple reading

Clear round rings are air bubbles in contact fluid, and hairs cross the field. They hide parts of the net and are not structures.

Canonical pattern: not linked. Air bubbles and hairs are contact-fluid and occlusion marks. They are not a skin pattern and are not added to the artifact library from one case.

Context and image information

Ruler and tick marks — Clearly visible; Conflicts with a simple reading

A ruler sits beside the clinical macule and black tick marks cross the dermoscopic field. They are scales, not skin.

Canonical pattern: measuring-scale-in-frame. Educational role: Image mark, not a skin finding. Case certainty and weight stay on this case.

Differential

Melanoma in situ

Why it fits: The net is uneven, with thicker central lines.; The outline is irregular.

Why not: The caption reports a nevus with cytologic atypia on histopathology.

Melanoma was a fair concern from the frames. Histopathology answered it for this lesion only.
Lentiginous melanocytic nevus with cytologic atypia

Why it fits: A brown net is present, which is a melanocytic look.; The caption reports this histopathology result.

Why not: Nothing in the frames proves a benign lesion.

The benign name comes from histopathology, not from a dermoscopic feature.
Common acquired nevus

Why it fits: A small brown macule with a net.

Why not: The net is uneven and the outline is irregular.

An ordinary-looking mole would not usually be excised for this net. This one was.

Closest mimic

Melanoma in situ

A histopathology-confirmed melanoma in situ in the same source figure shows a similar uneven net.

Why not

Melanoma in situ — The melanoma in situ in the same figure has a similar uneven net. These frames do not hold a feature that separates them; the caption's histopathology does.
Common acquired nevus — The net is uneven and the outline is irregular. That is why the lesion was excised rather than called ordinary.

Reasoning

The source labels these two frames as one case and reports a lentiginous melanocytic nevus with cytologic atypia on histopathology. The dermoscopic frame shows an uneven brown net like the melanoma in situ case in the same figure.

The uneven net is clearly visible and is the major reason melanoma was plausible. Bubbles, hairs, and ticks conflict if read as skin. The histopathology sentence is the confirmation. No dermoscopic feature in these frames argues strongly toward the benign result.

Diagnostic trap

Assuming that an excised lesion with an atypical net must be melanoma, or using this benign result to dismiss the next atypical net.

Mentor note

This is the benign half of a matched teaching pair from one figure. It teaches why melanoma was plausible and that histopathology, not a dermoscopic discriminator, answered the question.

Take-home rule

A benign histopathology result after an atypical net is an answer for that lesion. It is not a rule that atypical nets are benign.

Management brief

No management category is stored. The source reports excision and histopathology; that history is not a Docutis recommendation and is not reassurance for another lesion. This brief is not a protocol and remains review required.

A pink papule in the scalp (case-g25-03)

Teaching type: Reasoning case
Curriculum level: 4 · melanoma
Skills: Pink nodule, More than one vessel shape
Recorded diagnosis: Nodular melanoma, amelanotic
Disease record: nodular-melanoma
Confirmation: histopathology — The Figure 5 caption of Porto and coauthors (Scientific Reports 2022, doi:10.1038/s41598-022-17108-z), checked 2026-10-02, describes an amelanotic papule in the scalp vertex, says panel B is the dermoscopic image of the lesion, and states: Histopathological examination showed a nodular melanoma with a Breslow thickness of 5.5 mm. The subtype and thickness are the source's. No stage was added.
Site: Scalp vertex

Provenance

clinical · CC BY 4.0 · Ana Carolina Porto and coauthors

File: assets/media/cases/case-35-clinical.jpg

Source: Porto AC, Blumetti TP, Calsavara VF, Torrezan GT, de Paula CAA, Lellis R, Duprat Neto JP, Carraro DM, Braga JCT. Scientific Reports 2022, via PubMed Central (PMC9445057)

Porto and coauthors, Scientific Reports 2022, Figure 5 panel A, doi:10.1038/s41598-022-17108-z. CC BY 4.0. Cropped from the composite figure by Docutis.

Modification: cropped — Panel A of Figure 5 was cropped from the figure image embedded on page 8 of the article PDF in the PMC open-access package PMC9445057.1 (PDF image object 173, 1535 x 1003 pixels), source sha256 1ebeefcf60dd7388981435d264d7d913a2b09f4c3b69f8274b88a06273c42c7f, at pixel box left 0, top 0, right 832, bottom 1003 with Pillow, then saved as JPEG quality 90 without metadata. Output sha256 7c9e4b1d0ea2267c1081236b03baae270bb59208844324eb401cd961e1d0c9f0. No color change, no annotation, and no other edit.
dermoscopy · CC BY 4.0 · Ana Carolina Porto and coauthors

File: assets/media/cases/case-35-dermoscopy.jpg

Source: Porto AC, Blumetti TP, Calsavara VF, Torrezan GT, de Paula CAA, Lellis R, Duprat Neto JP, Carraro DM, Braga JCT. Scientific Reports 2022, via PubMed Central (PMC9445057)

Porto and coauthors, Scientific Reports 2022, Figure 5 panel B, doi:10.1038/s41598-022-17108-z. CC BY 4.0. Cropped from the composite figure by Docutis.

Modification: cropped — Panel B of Figure 5 was cropped from the figure image embedded on page 8 of the article PDF in the PMC open-access package PMC9445057.1 (PDF image object 173, 1535 x 1003 pixels), source sha256 1ebeefcf60dd7388981435d264d7d913a2b09f4c3b69f8274b88a06273c42c7f, at pixel box left 835, top 0, right 1535, bottom 1003 with Pillow, then saved as JPEG quality 90 without metadata. Output sha256 2ca1bc48d2f279b7c51a26dcd5fb31a40ce3f15baa14c82af8e4a053da6e2146. No color change, no annotation, and no other edit.

Observations

A pink dome-shaped papule sits in hair-bearing scalp. A small dark crust touches one side, and grey and white hairs cross the frame.
The field is pink. Fine purple-red lines run in short irregular curves in the center, and small red dots are scattered around them. A small orange-brown crust sits to one side. White hairs cross the field.

Observation prompts

How many different vessel shapes can you name?
Which parts of the dermoscopic field are hair or crust rather than vessels?

Features, certainty, and weight

Clinical morphology, dermoscopic structure, and image context are separate. An image mark does not compete with a diagnostic structure.

Clinical morphology

Pink papule without brown pigment — Clearly visible; Major clue

The papule is pink and dome-shaped, with no brown pigment in it. Missing pigment does not lower concern.

Canonical pattern: pink-nodule-without-pigment. Educational role: Descriptive morphology, not a dermoscopic structure. Case certainty and weight stay on this case.

Dermoscopic structure

Dotted and short linear vessels together — Probably present; Major clue

Fine irregular linear vessels and scattered red dots share one pink field. They are fine at this resolution, so the certainty is probable.

Canonical pattern: polymorphous-vessels. Educational role: Diagnostic structure. Case certainty and weight stay on this case.

Case-specific observation

Small orange-brown crust — Clearly visible; Supportive

A small orange-brown crust sits to one side. The caption calls the finding ulceration. No ulceration pattern was encoded from the caption.

Canonical pattern: not linked. A small orange-brown crust is visible. The caption calls it ulceration, and no ulceration pattern is created from a caption word and one frame.

Context and image information

None stored on this case.

Differential

Amelanotic nodular melanoma

Why it fits: A pink papule without brown pigment.; Dotted and short linear vessels together.; The caption reports histopathology.

Why not: Nothing in the frames proves a melanocytic tumor.

The vessel mix raises concern. The histopathology sentence names the tumor.
Nodular basal cell carcinoma

Why it fits: A pink papule on sun-exposed skin of an older adult.; Visible vessels on a pink field.

Why not: The vessels are short and mixed, not long sharp branching vessels.

Vessel shape is the comparison you can make in these frames. It is not proof.
Inflamed or traumatized benign papule

Why it fits: A crust is present.

Why not: Mixed vessels across a pink papule are not explained by a crust.

A crust is a reason to look again, not a reason to stop.

Closest mimic

Nodular basal cell carcinoma

A pink papule with visible vessels on sun-exposed skin is a common basal cell carcinoma look. The stored basal cell carcinoma dermoscopy case shows long branching vessels instead.

Why not

Nodular basal cell carcinoma — The stored basal cell carcinoma dermoscopy case shows long sharp branching vessels. This field shows short mixed vessels and dots. That difference raises concern; it does not exclude a basal cell carcinoma by itself.
Inflamed or traumatized benign papule — The crust is real, but it does not explain a mixed vessel pattern across the papule.

Reasoning

The source reports this scalp papule as a nodular melanoma on histopathology and says the dermoscopic frame is the same lesion. The clinical frame is a pink papule without pigment. The dermoscopic frame shows dotted and short linear vessels together and a small crust.

The pink papule is clearly visible and is the major clinical look. The vessel mix is probably visible and is the major dermoscopic clue. The crust is supportive. The histopathology sentence is the confirmation.

Diagnostic trap

Feeling reassured because there is no brown pigment, or calling every pink papule with vessels a basal cell carcinoma.

Mentor note

This is the second stored example of mixed vessels in Docutis and the first one paired with its clinical frame. Compare it with the basal cell carcinoma dermoscopy case: the vessel shapes, not the pink color, carry the comparison.

Take-home rule

A pink papule with more than one vessel shape needs a differential that includes amelanotic melanoma.

Management brief

No management category is stored. The source reports histopathology; that history is not a Docutis recommendation. This brief is not a protocol and remains review required.

A brown macule on the heel (case-g25-04)

Teaching type: Teaching case
Curriculum level: 3 · melanoma
Skills: Acral pigment, Parallel lines on palms and soles
Recorded diagnosis: Acral melanoma in situ
Disease record: acral-melanoma
Confirmation: histopathology — Figure 2 of Erol Mart and coauthors (International Journal of Dermatology 2026, doi:10.1111/ijd.70384), checked 2026-10-02, is titled melanoma in situ on the left heel. The methods state that for melanomas only pathology confirmed cases were included. The histopathology statement is study-level, not a sentence about this figure alone.
Site: Left heel, plantar sole

Provenance

clinical · CC BY 4.0 · Handan Merve Erol Mart and coauthors

File: assets/media/cases/case-36-clinical.jpg

Source: Erol Mart HM, Aydemir AT, Pietkiewicz P, Akay BN. International Journal of Dermatology 2026, via PubMed Central (PMC13342755)

Erol Mart and coauthors, International Journal of Dermatology 2026, Figure 2 panel a, doi:10.1111/ijd.70384. CC BY 4.0. Cropped from the composite figure by Docutis.

Modification: cropped — Panel a of Figure 2 was cropped from the figure image embedded on page 4 of the article PDF in the PMC open-access package PMC13342755.1 (PDF image object 8, 2081 x 1125 pixels), source sha256 d1f0bb44313b192ef232ff3ed21920d3d04c6b51265e97541d7927ad4a3a1207, at pixel box left 0, top 0, right 590, bottom 1125 with Pillow, then saved as JPEG quality 90 without metadata. Output sha256 f4104b35a6c946f1d3bcd99b4aab84fcdcabb9ce12ce7b75bc135d4ebff2b184. No color change, no annotation, and no other edit.
dermoscopy · CC BY 4.0 · Handan Merve Erol Mart and coauthors

File: assets/media/cases/case-36-dermoscopy.jpg

Source: Erol Mart HM, Aydemir AT, Pietkiewicz P, Akay BN. International Journal of Dermatology 2026, via PubMed Central (PMC13342755)

Erol Mart and coauthors, International Journal of Dermatology 2026, Figure 2 panel b, doi:10.1111/ijd.70384. CC BY 4.0. Cropped from the composite figure by Docutis.

Modification: cropped — Panel b of Figure 2 was cropped from the figure image embedded on page 4 of the article PDF in the PMC open-access package PMC13342755.1 (PDF image object 8, 2081 x 1125 pixels), source sha256 d1f0bb44313b192ef232ff3ed21920d3d04c6b51265e97541d7927ad4a3a1207, at pixel box left 593, top 0, right 1325, bottom 555 with Pillow, then saved as JPEG quality 90 without metadata. Output sha256 9daffc8492ea5c70b6a70c79ebac122ff5b35f07d35ef6af5a9fcf760406d7b4. No color change, no annotation, and no other edit.

Observations

A brown macule with an uneven edge sits on the heel of the sole. A fainter grey-brown smudge is elsewhere on the sole.
Brown pigment runs in many parallel bands across the lesion. The brown bands are broad and the pale lines between them are thin. A darker focus sits near the center, and the outer edge is uneven.

Observation prompts

Are the brown bands wider or narrower than the pale lines between them?
Is the site palm or sole skin?

Features, certainty, and weight

Clinical morphology, dermoscopic structure, and image context are separate. An image mark does not compete with a diagnostic structure.

Clinical morphology

None stored on this case.

Dermoscopic structure

Broad parallel pigmented bands on the sole — Probably present; Major clue

The pigmented bands are broad and the pale lines between them are thin, which favors pigment on the ridges. Sweat-duct openings are not resolved, so the certainty stays probable.

Canonical pattern: parallel-ridge-pattern. Educational role: Diagnostic structure. Case certainty and weight stay on this case.

Case-specific observation

Darker central focus — Clearly visible; Supportive

A darker brown focus sits near the center of the lesion. It is a case-specific observation.

Canonical pattern: not linked. A darker central focus is a case-specific observation, not a named acral structure.

Context and image information

None stored on this case.

Differential

Acral melanoma in situ

Why it fits: Pigment is in broad parallel bands, a ridge-type look.; The edge is uneven and a darker central focus is present.; The source states pathology confirmation for melanomas in the study.

Why not: No blue-white or vessel structure is visible.

The ridge-type bands are the clue. The source's pathology statement is the confirmation.
Acral melanocytic nevus

Why it fits: A flat brown macule on the sole.; Parallel lines are common in acral nevi.

Why not: In a typical acral nevus pattern the pigmented lines are thin and lie in the furrows; here the pigmented bands are broad.

Compare band widths before calling a parallel pattern benign.
Subcorneal haemorrhage

Why it fits: Pigment on the heel can be blood after friction.

Why not: The color is brown, not red-black, and it forms regular bands across the lesion.

Blood on the heel is a separate trap. No blood color is seen here.

Closest mimic

Acral melanocytic nevus

A flat brown macule with parallel lines on the sole is a common nevus look. No benign acral case with dermoscopy is stored yet in Docutis.

Why not

Acral melanocytic nevus — A typical acral nevus pattern places thin pigmented lines in the furrows. Here the pigmented bands are broad. That raises concern; it is not proof on its own.
Subcorneal haemorrhage — The color is brown and banded, not red-black. Blood is a separate heel trap.

Reasoning

The source titles this heel lesion melanoma in situ and states that melanomas in the study were pathology confirmed. The clinical frame shows a brown macule on the heel. The dermoscopic frame shows broad parallel brown bands with thin pale lines between them.

The parallel bands are clearly visible; their ridge assignment is probable and is the major clue. The darker focus is supportive. The study-level pathology statement is the confirmation and is weaker than a sentence about this lesion alone.

Diagnostic trap

Calling every parallel pattern on the sole a benign acral nevus, or deciding ridge versus furrow from the diagnosis rather than from the band widths.

Mentor note

This is the first acral dermoscopic case in Docutis. It joins the clinical-only plantar case. A benign acral comparison is still missing; do not treat this one case as the whole acral lesson.

Take-home rule

On the sole, compare band widths. Broad pigmented bands with thin pale lines are a ridge-type pattern and need a melanoma differential.

Management brief

No management category is stored. A ridge-type pattern in a teaching frame is not a decision to biopsy or refer for a real patient. This brief is not a protocol and remains review required.

A faint brown patch near the eye (case-g25-05)

Teaching type: Reasoning case
Curriculum level: 4 · melanoma
Skills: Pigment around facial follicles, Evidence weighting
Recorded diagnosis: Lentigo maligna (melanoma in situ)
Disease record: lentigo-maligna
Confirmation: histopathology — The Figure 1 caption of Rubegni and coauthors (Diagnostics 2024, doi:10.3390/diagnostics14222571), checked 2026-10-02, names this lesion a lentigo maligna in a 66-year-old male. The methods say the figure lesions come from the 80 study lesions and that the histological diagnosis was blinded until after the evaluation. The histopathology statement is study-level. The article calls lentigo maligna an in situ cutaneous melanoma.
Site: Face, periorbital region

Provenance

clinical · CC BY 4.0 · Giovanni Rubegni and coauthors

File: assets/media/cases/case-37-clinical.jpg

Source: Rubegni G, Cartocci A, Tognetti L, Orione M, Gagliano C, Bacci T, et al. Diagnostics 2024, via PubMed Central (PMC11593280)

Rubegni and coauthors, Diagnostics 2024, Figure 1 panel e, doi:10.3390/diagnostics14222571. CC BY 4.0. Cropped from the composite figure by Docutis.

Modification: cropped — Panel e of Figure 1 was cropped from the PMC figure file diagnostics-14-02571-g001b.jpg (second part of Figure 1, PMC open-access package PMC11593280.1), source sha256 4d45ed4504f7467436a184fc4a6730c17a3a756d2ced5bb4ff9a309a137c05fb, at pixel box left 5, top 337, right 385, bottom 624 with Pillow, then saved as JPEG quality 90 without metadata. Output sha256 87b65469afd3018110af5c11bfa0e68567566deab12ac4ffd5890b880ea4489b. No color change, no annotation, and no other edit.
dermoscopy · CC BY 4.0 · Giovanni Rubegni and coauthors

File: assets/media/cases/case-37-dermoscopy.jpg

Source: Rubegni G, Cartocci A, Tognetti L, Orione M, Gagliano C, Bacci T, et al. Diagnostics 2024, via PubMed Central (PMC11593280)

Rubegni and coauthors, Diagnostics 2024, Figure 1 panel f, doi:10.3390/diagnostics14222571. CC BY 4.0. Cropped from the composite figure by Docutis.

Modification: cropped — Panel f of Figure 1 was cropped from the PMC figure file diagnostics-14-02571-g001b.jpg (second part of Figure 1, PMC open-access package PMC11593280.1), source sha256 4d45ed4504f7467436a184fc4a6730c17a3a756d2ced5bb4ff9a309a137c05fb, at pixel box left 392, top 337, right 774, bottom 624 with Pillow, then saved as JPEG quality 90 without metadata. Output sha256 fef0a8958681e289991c09c06590f58c493974aa1264101aa7b54441f5ded070. No color change, no annotation, and no other edit.

Observations

A faint brown patch sits on sun-damaged skin of the side of the face near the hairline and the outer corner of the eye. Redness and fine vessels are around it.
Brown pigment is broken by many pale round follicular openings. Gray and gray-brown dots cluster around several openings, and the pigment is darker and denser on one side. Hairs cross the field.

Observation prompts

What sits around the pale round openings?
Is the pigment even, or darker on one side?

Features, certainty, and weight

Clinical morphology, dermoscopic structure, and image context are separate. An image mark does not compete with a diagnostic structure.

Clinical morphology

None stored on this case.

Dermoscopic structure

Gray dots around follicular openings — Probably present; Major clue

Gray and gray-brown dots cluster around several pale openings. Their arrangement around the openings is clear in parts of the field and less clear elsewhere, so the certainty is probable.

Canonical pattern: perifollicular-gray-dots. Educational role: Diagnostic structure. Case certainty and weight stay on this case.
Brown pigment broken by pale openings — Clearly visible; Weak

Pale round follicular openings break the brown pigment into a net-like look. The same background is on the benign facial case.

Canonical pattern: facial-pseudonetwork. Educational role: Diagnostic structure. Case certainty and weight stay on this case.

Case-specific observation

Pigment darker on one side — Clearly visible; Supportive

The pigment is denser and darker on one side of the field. This is a case-specific asymmetry, not a named structure.

Canonical pattern: not linked. Pigment darker on one side is case-specific asymmetry. Asymmetric pigmented follicular openings were not claimed as a separate structure at this resolution.

Context and image information

None stored on this case.

Differential

Lentigo maligna

Why it fits: Gray dots cluster around follicular openings.; Pigment is darker and denser on one side.; The source names this lesion and reports study-level histology.

Why not: Rhomboidal structures are not clear.

Gray around the follicles is the clue. The source's histology statement is the confirmation.
Solar lentigo

Why it fits: Brown facial pigment with a pseudo-network.

Why not: Gray dots around follicles are visible here and are not seen on the stored solar lentigo frame.

Both show a pseudo-network. What surrounds the openings differs in these two frames.
Pigmented actinic keratosis

Why it fits: Sun-damaged facial skin with brown pigment and redness.

Why not: No scale is clear on the dermoscopic frame.

Pigmented actinic keratosis is a real facial mimic. It is not stored as a Docutis case yet.

Closest mimic

Solar lentigo

A flat brown facial patch with a pseudo-network is also the look of a solar lentigo. The stored facial solar lentigo case shows no gray dots around follicles.

Why not

Solar lentigo — The stored facial solar lentigo has a pseudo-network without gray dots around the openings. This frame has gray dots. That difference raises concern; it is not proof.
Pigmented actinic keratosis — Pigmented actinic keratosis is a facial mimic, but scale is not clear here. It stays in the differential and is not stored as a case.

Reasoning

The source names this periorbital lesion a lentigo maligna and reports study-level histology. The clinical frame is a faint brown patch on sun-damaged skin. The dermoscopic frame shows a pseudo-network with gray dots around follicular openings and lopsided darker pigment.

Gray dots around follicles are probably visible and are the major clue. Lopsided darker pigment is supportive. The pseudo-network is clearly visible but weak, because the benign facial case has it too. The study-level histology statement is the confirmation.

Diagnostic trap

Treating the pseudo-network as the clue, or calling every faint brown facial patch a solar lentigo.

Mentor note

Read this case beside the facial solar lentigo from the same figure. Both have a pseudo-network. Only this one has gray dots around the openings.

Take-home rule

On facial skin, look at the follicular openings. Gray around them is a reason for concern; a pseudo-network alone is not.

Management brief

No management category is stored. Gray dots around follicles in a teaching frame are not a decision to biopsy or refer for a real patient. This brief is not a protocol and remains review required.

A light brown patch on the eyelid (case-g25-06)

Teaching type: Teaching case
Curriculum level: 3 · mimic
Skills: Pigment around facial follicles
Recorded diagnosis: Solar lentigo
Disease record: solar-lentigo
Confirmation: histopathology — The Figure 1 caption of Rubegni and coauthors (Diagnostics 2024, doi:10.3390/diagnostics14222571), checked 2026-10-02, names this lesion a solar lentigo in a 71-year-old woman. The methods say the figure lesions come from the 80 study lesions and that the histological diagnosis was blinded until after the evaluation. The histopathology statement is study-level.
Site: Face, periorbital region, upper eyelid

Provenance

clinical · CC BY 4.0 · Giovanni Rubegni and coauthors

File: assets/media/cases/case-38-clinical.jpg

Source: Rubegni G, Cartocci A, Tognetti L, Orione M, Gagliano C, Bacci T, et al. Diagnostics 2024, via PubMed Central (PMC11593280)

Rubegni and coauthors, Diagnostics 2024, Figure 1 panel c, doi:10.3390/diagnostics14222571. CC BY 4.0. Cropped from the composite figure by Docutis.

Modification: cropped — Panel c of Figure 1 was cropped from the PMC figure file diagnostics-14-02571-g001b.jpg (second part of Figure 1, PMC open-access package PMC11593280.1), source sha256 4d45ed4504f7467436a184fc4a6730c17a3a756d2ced5bb4ff9a309a137c05fb, at pixel box left 5, top 3, right 385, bottom 290 with Pillow, then saved as JPEG quality 90 without metadata. Output sha256 236d7086e2495282b237cf06cc1c5a0def14f5b04a8b7f0487c6eb909f9cfc66. No color change, no annotation, and no other edit.
dermoscopy · CC BY 4.0 · Giovanni Rubegni and coauthors

File: assets/media/cases/case-38-dermoscopy.jpg

Source: Rubegni G, Cartocci A, Tognetti L, Orione M, Gagliano C, Bacci T, et al. Diagnostics 2024, via PubMed Central (PMC11593280)

Rubegni and coauthors, Diagnostics 2024, Figure 1 panel d, doi:10.3390/diagnostics14222571. CC BY 4.0. Cropped from the composite figure by Docutis.

Modification: cropped — Panel d of Figure 1 was cropped from the PMC figure file diagnostics-14-02571-g001b.jpg (second part of Figure 1, PMC open-access package PMC11593280.1), source sha256 4d45ed4504f7467436a184fc4a6730c17a3a756d2ced5bb4ff9a309a137c05fb, at pixel box left 392, top 3, right 774, bottom 290 with Pillow, then saved as JPEG quality 90 without metadata. Output sha256 bddac1356b8dbf0db117bbbad53323366b139536d44d2f290c2ecf822a4012f6. No color change, no annotation, and no other edit.

Observations

A light brown patch with darker brown parts sits on the upper eyelid fold of a closed eye. Fine wrinkles cross the skin.
Orange-brown pigment is broken by pale round follicular openings. Thin red vessels and white scale lie at the edges. Gray dots around the openings are not seen. Tick marks run along the lower edge.

Observation prompts

What color surrounds the pale openings?
Which lines along the edge are scale ticks rather than skin?

Features, certainty, and weight

Clinical morphology, dermoscopic structure, and image context are separate. An image mark does not compete with a diagnostic structure.

Clinical morphology

None stored on this case.

Dermoscopic structure

Orange-brown pigment broken by pale openings — Clearly visible; Supportive

Pale round openings break orange-brown pigment into a net-like look. The same background appears on the facial lentigo maligna case, so it does not separate them.

Canonical pattern: facial-pseudonetwork. Educational role: Diagnostic structure. Case certainty and weight stay on this case.
Gray dots around follicles not seen — Not visible in this image; Supportive

No gray dots cluster around the openings in this frame. That absence is consistent with the source diagnosis and is not a clearance.

Canonical pattern: perifollicular-gray-dots. Educational role: Diagnostic structure. Case certainty and weight stay on this case.

Case-specific observation

None stored on this case.

Context and image information

Tick marks along the edge — Clearly visible; Conflicts with a simple reading

Tick marks run along the lower edge of the dermoscopic field. They are a scale, not skin.

Canonical pattern: measuring-scale-in-frame. Educational role: Image mark, not a skin finding. Case certainty and weight stay on this case.

Differential

Solar lentigo

Why it fits: Orange-brown pseudo-network.; No gray dots around follicles in this frame.; The source names this lesion and reports study-level histology.

Why not: Darker parts in the clinical patch.

The benign name comes from the source's histology statement. The missing gray supports it in this frame.
Lentigo maligna

Why it fits: A brown patch on sun-damaged periorbital skin with a pseudo-network.; The source figure shows lentigo maligna with a similar clinical look.

Why not: Gray dots around follicles are not seen.

Lentigo maligna was a fair concern. Missing gray in one frame is not a clearance.
Seborrheic keratosis

Why it fits: Brown facial pigment in an older adult.

Why not: No ridges, comedo-like openings, or thick rough surface are seen.

A keratosis is in the facial differential; this frame lacks its surface.

Closest mimic

Lentigo maligna

A flat brown periorbital patch with a pseudo-network is also the look of lentigo maligna. The stored facial lentigo maligna case shows gray dots around follicles.

Why not

Lentigo maligna — The facial lentigo maligna case shows gray dots around follicles. This frame does not. That difference supports the source diagnosis here and is not a rule.
Seborrheic keratosis — No ridges, comedo-like openings, or rough surface are seen.

Reasoning

The source names this periorbital lesion a solar lentigo and reports study-level histology. The clinical frame is a light brown eyelid patch with darker parts. The dermoscopic frame shows an orange-brown pseudo-network without gray dots around the openings.

The pseudo-network is clearly visible but supportive only, because the facial lentigo maligna case has it too. The absence of gray dots around follicles is supportive for the source diagnosis in this frame. The study-level histology statement is the confirmation.

Diagnostic trap

Taking reassurance from a pseudo-network, or treating one benign periorbital result as a rule for the next patch.

Mentor note

This is the benign half of a facial pair from one figure. It teaches why lentigo maligna was plausible and what in this frame argues toward the benign result: no gray around the follicles.

Take-home rule

On facial skin, a pseudo-network is a background. Check the follicles for gray before you accept a benign name, and keep histopathology in mind when in doubt.

Management brief

No management category is stored. A benign source label is not reassurance for another facial patch. This brief is not a protocol and remains review required.

A small brown macule on the heel with a dark centre (case-g26-01)

Teaching type: Reasoning case
Curriculum level: 4 · melanoma
Skills: Parallel lines on palms and soles, Asymmetry
Recorded diagnosis: Acral melanoma
Disease record: acral-melanoma
Confirmation: histopathology — The Figure 2 caption of Tognetti and coauthors (Life 2024, doi:10.3390/life14060659), checked 2026-10-02, names this heel lesion a melanoma. The methods state that every lesion in the dataset was excised for histopathology and that a definitive histopathological diagnosis was mandatory. The subtype, thickness, and stage of this lesion are not given and were not added.
Site: Heel, plantar sole

Provenance

clinical · CC BY 4.0 · Linda Tognetti and coauthors

File: assets/media/cases/case-39-clinical.jpg

Source: Tognetti L, Cartocci A, Moscarella E, Lallas A, Dika E, Fargnoli MC, Longo C, Nazzaro G, et al. Life 2024, via PubMed Central (PMC11205239)

Tognetti and coauthors, Life 2024, Figure 2 panel a, doi:10.3390/life14060659. CC BY 4.0. Cropped from the composite figure by Docutis.

Modification: cropped — Panel a of Figure 2 was cropped from the PMC figure file life-14-00659-g002.jpg (PMC open-access package PMC11205239.1), source sha256 d88de7a2b4710b95ee18d53a4cd3da553e36ce7d589188352e7a4f6e78aec811, at pixel box left 3, top 5, right 339, bottom 238 with Pillow, then saved as JPEG quality 90 without metadata. Output sha256 660e673113fce96e8d57d47b4619f58a2e4cbe3ec90e79e2955a8b24dba763da. No color change, no annotation, and no other edit.
dermoscopy · CC BY 4.0 · Linda Tognetti and coauthors

File: assets/media/cases/case-39-dermoscopy.jpg

Source: Tognetti L, Cartocci A, Moscarella E, Lallas A, Dika E, Fargnoli MC, Longo C, Nazzaro G, et al. Life 2024, via PubMed Central (PMC11205239)

Tognetti and coauthors, Life 2024, Figure 2 panel b, doi:10.3390/life14060659. CC BY 4.0. Cropped from the composite figure by Docutis.

Modification: cropped — Panel b of Figure 2 was cropped from the PMC figure file life-14-00659-g002.jpg (PMC open-access package PMC11205239.1), source sha256 d88de7a2b4710b95ee18d53a4cd3da553e36ce7d589188352e7a4f6e78aec811, at pixel box left 345, top 5, right 680, bottom 238 with Pillow, then saved as JPEG quality 90 without metadata. Output sha256 8b62dacad21b96b5b2c36538df8e9176ed29a0eb5b081814ad008f385434b698. No color change, no annotation, and no other edit.

Observations

A small brown macule on the heel. Its centre is darker and elongated, and lighter brown extends to one side.
Brown pigment of several shades spreads unevenly. A darker brown-violet irregular blotch sits near the centre, and lighter brown areas lie at the edges. No regular rows of lines or broad parallel bands organize the pigment.

Observation prompts

Is the pigment arranged in regular rows or bands?
Where is the darkest area, and is it centred?

Features, certainty, and weight

Clinical morphology, dermoscopic structure, and image context are separate. An image mark does not compete with a diagnostic structure.

Clinical morphology

None stored on this case.

Dermoscopic structure

Uneven brown pigment with a dark off-centre blotch — Probably present; Major clue

Several browns and a darker violet-brown blotch, without regular rows. The panel is small, so the certainty is probable.

Canonical pattern: irregular-acral-pigmentation. Educational role: Diagnostic structure. Case certainty and weight stay on this case.
Broad parallel pigmented bands — Not visible in this image; Weak

Broad bands following the skin markings are not visible here. Their absence does not lower concern.

Canonical pattern: parallel-ridge-pattern. Educational role: Diagnostic structure. Case certainty and weight stay on this case.

Case-specific observation

None stored on this case.

Context and image information

None stored on this case.

Differential

Acral melanoma

Why it fits: Irregular pigment with a dark blotch.; The source reports study-level histopathology.

Why not: No parallel ridge pattern is visible.

Irregular pigment carries the concern here, not a ridge pattern.
Acral melanocytic nevus

Why it fits: A small brown heel macule.; A heel nevus of the same size in the same figure looks similar clinically.

Why not: The pigment is not arranged in regular rows.

The nevus in the same figure shows regular fine rows. This frame does not.
Subcorneal haematoma

Why it fits: Dark colour on a heel.

Why not: The colour is brown and violet rather than red to maroon.

Blood on the heel is a separate trap; the colour here is not the blood colour.

Closest mimic

Acral melanocytic nevus

A heel nevus of similar size in a woman of the same age, in the same source figure, looks similar clinically.

Why not

Acral melanocytic nevus — The nevus in the same figure shows fine strokes in regular rows. This frame shows irregular pigment with a blotch. That difference raises concern; it is not proof.
Subcorneal haematoma — Blood is red to maroon. This pigment is brown and violet.

Reasoning

The source names this heel lesion a melanoma and reports that every lesion in the study was excised for histopathology. The dermoscopic frame shows irregular brown pigment with a dark blotch and no parallel ridge pattern.

Irregular pigment with a blotch is probably visible and is the major clue. The missing ridge pattern has weak weight and does not argue against the diagnosis. The study-level histopathology statement is the confirmation.

Diagnostic trap

Waiting for a parallel ridge pattern before taking an irregular acral lesion seriously.

Mentor note

Read this case beside the heel nevus from the same figure: same site, same age, same size, different organization of pigment. Neither frame has a parallel ridge pattern.

Take-home rule

On acral skin, irregular pigment with a blotch is a reason for concern even when no ridge pattern is present.

Management brief

No management category is stored. The source history is not a Docutis recommendation. This brief is not a protocol and remains review required.

A faint brown spot on the heel (case-g26-02)

Teaching type: Teaching case
Curriculum level: 3 · mimic
Skills: Parallel lines on palms and soles
Recorded diagnosis: Acral melanocytic nevus
Disease record: melanocytic-nevus
Confirmation: histopathology — The Figure 2 caption of Tognetti and coauthors (Life 2024, doi:10.3390/life14060659), checked 2026-10-02, names this heel lesion a nevus with a regular fibrillar pattern. The methods state that every lesion was excised for histopathology. The accepted benign histopathologic diagnoses in the study range from nevus with mild atypia to SAMPUS; the grade for this lesion is not given and was not added.
Site: Heel, plantar sole

Provenance

clinical · CC BY 4.0 · Linda Tognetti and coauthors

File: assets/media/cases/case-40-clinical.jpg

Source: Tognetti L, Cartocci A, Moscarella E, Lallas A, Dika E, Fargnoli MC, Longo C, Nazzaro G, et al. Life 2024, via PubMed Central (PMC11205239)

Tognetti and coauthors, Life 2024, Figure 2 panel c, doi:10.3390/life14060659. CC BY 4.0. Cropped from the composite figure by Docutis.

Modification: cropped — Panel c of Figure 2 was cropped from the PMC figure file life-14-00659-g002.jpg (PMC open-access package PMC11205239.1), source sha256 d88de7a2b4710b95ee18d53a4cd3da553e36ce7d589188352e7a4f6e78aec811, at pixel box left 3, top 242, right 339, bottom 477 with Pillow, then saved as JPEG quality 90 without metadata. Output sha256 c41f67584104b83870cf69a30960c5a56ddeb81b64fd914e45b27af09ef1f7c0. No color change, no annotation, and no other edit.
dermoscopy · CC BY 4.0 · Linda Tognetti and coauthors

File: assets/media/cases/case-40-dermoscopy.jpg

Source: Tognetti L, Cartocci A, Moscarella E, Lallas A, Dika E, Fargnoli MC, Longo C, Nazzaro G, et al. Life 2024, via PubMed Central (PMC11205239)

Tognetti and coauthors, Life 2024, Figure 2 panel d, doi:10.3390/life14060659. CC BY 4.0. Cropped from the composite figure by Docutis.

Modification: cropped — Panel d of Figure 2 was cropped from the PMC figure file life-14-00659-g002.jpg (PMC open-access package PMC11205239.1), source sha256 d88de7a2b4710b95ee18d53a4cd3da553e36ce7d589188352e7a4f6e78aec811, at pixel box left 345, top 242, right 680, bottom 477 with Pillow, then saved as JPEG quality 90 without metadata. Output sha256 d6dd02fb146cd163dec44e15e2d4953be1526fa721e67143805f08fd8c4eacdb. No color change, no annotation, and no other edit.

Observations

A heel with scale and creases. A faint small brown spot sits where a printed cyan arrow points.
Fine short brown strokes lie obliquely in evenly spaced parallel rows across the whole lesion. The pale spaces between rows are as wide as or wider than the brown strokes. The colour is a single light brown, and no blotch is present.

Observation prompts

Are the brown strokes evenly spaced in rows?
Is there a darker blotch anywhere in the lesion?

Features, certainty, and weight

Clinical morphology, dermoscopic structure, and image context are separate. An image mark does not compete with a diagnostic structure.

Clinical morphology

None stored on this case.

Dermoscopic structure

Fine oblique strokes in regular rows — Probably present; Major clue

Evenly spaced rows of fine oblique strokes across the whole lesion. Furrow orientation is not resolved, so the certainty is probable.

Canonical pattern: fibrillar-pattern. Educational role: Diagnostic structure. Case certainty and weight stay on this case.
Broad parallel pigmented bands — Not visible in this image; Supportive

The brown lines are thin, with pale spaces at least as wide. Broad ridge-type bands are not visible.

Canonical pattern: parallel-ridge-pattern. Educational role: Diagnostic structure. Case certainty and weight stay on this case.

Case-specific observation

None stored on this case.

Context and image information

Printed arrow in the clinical frame — Clearly visible; Conflicts with a simple reading

A cyan arrow printed on the photograph points to the spot. It is a mark, not skin.

Canonical pattern: printed-pointer. Educational role: Image mark, not a skin finding. Case certainty and weight stay on this case.

Differential

Acral melanocytic nevus

Why it fits: Fine strokes in regular, evenly spaced rows.; One colour, no blotch.; The source reports study-level histopathology.

Why not: The lesion was excised, so it was not obviously benign to the clinicians.

Regular organization supports the benign source diagnosis in this frame.
Acral melanoma

Why it fits: A brown acral macule in an adult.; A heel melanoma of similar size in the same figure looked similar clinically.

Why not: No irregular blotch and no broad ridge bands are seen.

Melanoma was a fair concern on the clinical look.
Subcorneal haematoma

Why it fits: A spot on a pressure-bearing heel.

Why not: The colour is light brown and organized in rows, not red to maroon and structureless.

A heel spot is not automatically blood.

Closest mimic

Acral melanoma

A heel melanoma of similar size in a woman of the same age, in the same source figure, looks similar clinically.

Why not

Acral melanoma — The heel melanoma in the same figure shows irregular pigment with a blotch. This frame shows regular rows. That difference supports the source diagnosis here; it is not a rule.
Subcorneal haematoma — The colour is light brown and organized in rows, not red to maroon and structureless.

Reasoning

The source names this heel lesion a nevus and reports that every lesion in the study was excised for histopathology. The dermoscopic frame shows fine oblique strokes in regular rows, without broad ridge bands or a blotch.

Regular rows are probably visible and are the major clue toward the source diagnosis. The missing ridge bands support it. The arrow conflicts only if read as skin. The study-level histopathology statement is the confirmation.

Diagnostic trap

Treating any parallel acral pattern as benign, or treating one benign heel result as a rule.

Mentor note

This is the benign half of a heel pair from one figure. It teaches why melanoma was plausible and what in this frame argues toward the benign result: regular organization.

Take-home rule

On acral skin, regular evenly spaced fine lines without a blotch support a benign reading in this frame. Irregularity anywhere changes the weighting.

Management brief

No management category is stored. The source history is not a Docutis recommendation. This brief is not a protocol and remains review required.

A dark brown macule on the sole (case-g26-03)

Teaching type: Reasoning case
Curriculum level: 4 · melanoma
Skills: Parallel lines on palms and soles, Evidence weighting
Recorded diagnosis: Acral lentiginous melanoma in situ
Disease record: acral-melanoma
Confirmation: histopathology — The Figure 1 caption of Han and coauthors (Scientific Reports 2020, doi:10.1038/s41598-020-77425-z), checked 2026-10-02, describes panels A and B as a 12 mm acral lentiginous melanoma in situ with asymmetry, irregular dots and globules, and an irregular fibrillar pattern. The methods state that all cases were diagnosed on clinical, dermoscopic, and histopathologic criteria after biopsy.
Site: Sole of the foot, plantar

Provenance

clinical · CC BY 4.0 · Byeol Han and coauthors

File: assets/media/cases/case-41-clinical.jpg

Source: Han B, Hur K, Ohn J, Lim SS, Mun JH. Scientific Reports 2020, via PubMed Central (PMC7688656)

Han and coauthors, Scientific Reports 2020, Figure 1 panel A, doi:10.1038/s41598-020-77425-z. CC BY 4.0. Cropped from the composite figure by Docutis.

Modification: cropped — Panel A of Figure 1 was cropped from the figure image embedded on page 3 of the article PDF in the PMC open-access package PMC7688656 (PDF image object 49, 1417 x 1027 pixels), source sha256 69162dde8e946e84fcad28de0a0214b10f1816c9af963129b9e31c1fd73de5f6, at pixel box left 0, top 0, right 708, bottom 512 with Pillow, then saved as JPEG quality 90 without metadata. Output sha256 a8ae418a4ed636e57a6668f2581248a1ecc699eb429e57df81970167342b97ca. No color change, no annotation, and no other edit.
dermoscopy · CC BY 4.0 · Byeol Han and coauthors

File: assets/media/cases/case-41-dermoscopy.jpg

Source: Han B, Hur K, Ohn J, Lim SS, Mun JH. Scientific Reports 2020, via PubMed Central (PMC7688656)

Han and coauthors, Scientific Reports 2020, Figure 1 panel B, doi:10.1038/s41598-020-77425-z. CC BY 4.0. Cropped from the composite figure by Docutis.

Modification: cropped — Panel B of Figure 1 was cropped from the figure image embedded on page 3 of the article PDF in the PMC open-access package PMC7688656 (PDF image object 49, 1417 x 1027 pixels), source sha256 69162dde8e946e84fcad28de0a0214b10f1816c9af963129b9e31c1fd73de5f6, at pixel box left 709, top 0, right 1417, bottom 512 with Pillow, then saved as JPEG quality 90 without metadata. Output sha256 5f821c919e73195a82d55547398349bf0ada93267aad05eb2530fe009e137f6b. No color change, no annotation, and no other edit.

Observations

A dark brown irregular macule sits on the sole of the foot, between the heel and the forefoot.
Short brown strokes and small brown dots spread unevenly across the lesion. Some areas are dense and dark and others sparse and pale. Many strokes lie obliquely along the skin markings. A printed millimetre scale and the label 3cm sit at the left edge.

Observation prompts

Are the strokes evenly spaced, or dense in some areas and sparse in others?
Which marks at the edge are printed rather than skin?

Features, certainty, and weight

Clinical morphology, dermoscopic structure, and image context are separate. An image mark does not compete with a diagnostic structure.

Clinical morphology

None stored on this case.

Dermoscopic structure

Uneven oblique strokes mixed with dots — Probably present; Major clue

Short oblique strokes and dots of varying darkness are spread unevenly. Ridge or furrow position is not resolved, so the certainty is probable.

Canonical pattern: fibrillar-pattern. Educational role: Diagnostic structure. Case certainty and weight stay on this case.
Broad parallel pigmented bands — Uncertain; Weak

Some strokes follow the skin markings, but broad ridge-type bands cannot be confirmed in this frame.

Canonical pattern: parallel-ridge-pattern. Educational role: Diagnostic structure. Case certainty and weight stay on this case.

Case-specific observation

None stored on this case.

Context and image information

Printed scale and label — Clearly visible; Conflicts with a simple reading

A millimetre scale and the label 3cm are printed at the left edge. They are not skin.

Canonical pattern: measuring-scale-in-frame. Educational role: Image mark, not a skin finding. Case certainty and weight stay on this case.

Differential

Acral lentiginous melanoma in situ

Why it fits: Uneven strokes and dots.; Asymmetric distribution of pigment.; The source reports study-level histopathology.

Why not: No broad ridge bands are claimed.

Irregularity of a fibrillar-type pattern carries the concern here.
Acral melanocytic nevus

Why it fits: Oblique strokes on a sole can be a nevus pattern.

Why not: The strokes are uneven and mixed with dots, not regular rows.

The regular heel nevus is the comparison: same stroke type, different regularity.
Subcorneal haematoma

Why it fits: A dark spot on the sole.

Why not: The colour is brown and structured, not red to maroon and homogeneous.

Blood is a separate acral trap.

Closest mimic

Acral melanocytic nevus

Oblique strokes are a common acral nevus look; the regular heel nevus in Docutis shows them in even rows.

Why not

Acral melanocytic nevus — The heel nevus shows the same stroke type in regular rows. Here the strokes are uneven and mixed with dots.
Subcorneal haematoma — The colour is brown and structured, not red to maroon and homogeneous.

Reasoning

The source describes this sole lesion as an acral lentiginous melanoma in situ diagnosed on histopathologic criteria. The dermoscopic frame shows oblique strokes and dots spread unevenly, an irregular version of the stroke pattern that the heel nevus shows in regular rows.

Uneven strokes with dots are probably visible and are the major clue. A ridge pattern is uncertain and has weak weight. The printed scale conflicts if read as skin. The study-level histopathology statement is the confirmation.

Diagnostic trap

Calling every oblique stroke pattern benign because the strokes look like a nevus pattern.

Mentor note

This case and the heel nevus share a stroke type. Regularity, not the stroke itself, separates them in these two frames.

Take-home rule

The same acral stroke pattern can be regular or irregular. Irregular spacing, colour, and dots raise concern.

Management brief

No management category is stored. The source history is not a Docutis recommendation. This brief is not a protocol and remains review required.

A dark spot on a fingertip (case-g26-04)

Teaching type: Teaching case
Curriculum level: 3 · mimic
Skills: Acral pigment, Blood colour on acral skin
Recorded diagnosis: Subcorneal haematoma
Disease record: subcorneal-haemorrhage
Confirmation: clinical_diagnosis — Martinez-Ortega and coauthors (Cureus 2026, doi:10.7759/cureus.109272), checked 2026-10-02, favoured subcorneal haematoma on clinical and dermoscopic grounds and report complete spontaneous resolution at one-month follow-up. The article states that histopathologic confirmation was not obtained.
Site: Volar fingertip, acral skin

Provenance

clinical · CC BY 4.0 · Jesus Ivan Martinez-Ortega and coauthors

File: assets/media/cases/case-42-clinical.jpg

Source: Martinez-Ortega JI, Naidnur S, et al. Cureus 2026, via PubMed Central (PMC13282028)

Martinez-Ortega and coauthors, Cureus 2026, Figure 1 panel A, doi:10.7759/cureus.109272. CC BY 4.0. Cropped from the composite figure by Docutis.

Modification: cropped — Panel A of Figure 1 was cropped from the PMC figure file cureus-0018-00000109272-i01.jpg (PMC open-access package PMC13282028), source sha256 8911a97db3ca9237d02ef502db910214f75a474d1fb273f3e5e1262546441140, at pixel box left 0, top 0, right 333, bottom 516 with Pillow, then saved as JPEG quality 90 without metadata. Output sha256 fee1fd03ba7008eab2912ee334298b501fc5a7de361143e3ccb4c32508c4d957. No color change, no annotation, and no other edit.
dermoscopy · CC BY 4.0 · Jesus Ivan Martinez-Ortega and coauthors

File: assets/media/cases/case-42-dermoscopy.jpg

Source: Martinez-Ortega JI, Naidnur S, et al. Cureus 2026, via PubMed Central (PMC13282028)

Martinez-Ortega and coauthors, Cureus 2026, Figure 1 panel B, doi:10.7759/cureus.109272. CC BY 4.0. Cropped from the composite figure by Docutis.

Modification: cropped — Panel B of Figure 1 was cropped from the PMC figure file cureus-0018-00000109272-i01.jpg (PMC open-access package PMC13282028), source sha256 8911a97db3ca9237d02ef502db910214f75a474d1fb273f3e5e1262546441140, at pixel box left 336, top 0, right 749, bottom 516 with Pillow, then saved as JPEG quality 90 without metadata. Output sha256 954b3275dc826e5e85c24350fc57391992caecaf5d7ee9fb77b9bb841250fb9c. No color change, no annotation, and no other edit.

Observations

A palm and fingers. A small dark spot sits on the volar tip of the index finger.
A sharply bordered homogeneous red to maroon area with fine white cracks and white scale at one side. No lines, network, or brown dots are present. A printed millimetre scale lies below.

Observation prompts

Is the colour brown, or red to maroon?
Are any lines or a network visible inside the spot?

Features, certainty, and weight

Clinical morphology, dermoscopic structure, and image context are separate. An image mark does not compete with a diagnostic structure.

Clinical morphology

None stored on this case.

Dermoscopic structure

Homogeneous red to maroon area — Clearly visible; Major clue

A sharply bordered red to maroon structureless area without lines. It fits blood in this frame and does not exclude a lesion under it.

Canonical pattern: hemorrhagic-structureless-area. Educational role: Diagnostic structure. Case certainty and weight stay on this case.
Broad parallel pigmented bands — Not visible in this image; Supportive

No bands or lines of any kind are visible.

Canonical pattern: parallel-ridge-pattern. Educational role: Diagnostic structure. Case certainty and weight stay on this case.

Case-specific observation

None stored on this case.

Context and image information

Printed millimetre scale — Clearly visible; Conflicts with a simple reading

A printed scale lies below the spot. It is not skin.

Canonical pattern: measuring-scale-in-frame. Educational role: Image mark, not a skin finding. Case certainty and weight stay on this case.

Differential

Subcorneal haematoma

Why it fits: Homogeneous red to maroon colour.; No melanocytic lines or network.; The source reports resolution at follow-up.

Why not: The patient history of trauma is not stored.

The colour and the follow-up carry this diagnosis, not histopathology.
Acral melanoma

Why it fits: A dark acral spot on a finger.

Why not: No brown lines, blotch, or irregular pigmentation is visible.

Blood can hide pigment. Follow-up or a scraping test is how the source settled it.
Acral melanocytic nevus

Why it fits: A small acral macule.

Why not: No brown lines or rows are visible.

A nevus would show brown lines on acral skin.

Closest mimic

Acral melanoma

A dark spot on acral skin is the classic acral melanoma worry, and blood can mimic or hide pigment.

Why not

Acral melanoma — No brown lines, blotch, or irregular pigmentation is visible, and the spot resolved. A spot that persists needs reassessment.
Acral melanocytic nevus — No brown lines or rows are visible.

Reasoning

The source favoured subcorneal haematoma and reports complete resolution at one month without histopathology. The dermoscopic frame shows a homogeneous red to maroon area without lines.

The blood colour is clearly visible and is the major clue. The missing line pattern supports it. Resolution at follow-up is the confirmation, which is weaker than histopathology.

Diagnostic trap

Reassuring from colour alone without follow-up or a scraping test, or calling dark blood brown melanin.

Mentor note

This is the blood pole of the acral cluster. Compare its colour and lack of structure with the heel melanoma that shows irregular brown pigment.

Take-home rule

Red to maroon structureless acral colour suggests blood. Confirm with follow-up or scraping before you let it go.

Management brief

No management category is stored. The source history is not a Docutis recommendation. This brief is not a protocol and remains review required.

A brown band on a child's toenail (case-g26-05)

Teaching type: Teaching case
Curriculum level: 3 · mimic
Skills: Pigmented nail band
Recorded diagnosis: Junctional melanocytic nevus of the nail unit
Disease record: melanocytic-nevus
Confirmation: histopathology — Morato and coauthors (Anais Brasileiros de Dermatologia 2022, doi:10.1016/j.abd.2021.02.012), checked 2026-10-02, report for Case 2 that the histopathology of a tangential biopsy was compatible with a junctional melanocytic nevus. The biopsy followed the first-consultation images in Figure 2 A and B. The band then stayed stable for five years.
Site: Second left toe, nail unit

Provenance

clinical · CC BY 4.0 · Isabela Boechat Morato and coauthors

File: assets/media/cases/case-43-clinical.jpg

Source: Morato IB, Gontijo JRV, Tavares GT, Bittencourt FV. Anais Brasileiros de Dermatologia 2022, via PubMed Central (PMC9263629)

Morato and coauthors, Anais Brasileiros de Dermatologia 2022, Figure 2 panel A, doi:10.1016/j.abd.2021.02.012. CC BY 4.0. Cropped from the composite figure by Docutis.

Modification: cropped — Panel A of Figure 2 was cropped from the figure image embedded on page 2 of the article PDF in the PMC open-access package PMC9263629 (PDF image object 5, 1505 x 1312 pixels), source sha256 dcdbf421339af5fedce5254f23551450d07a3b4df57f9d1ce3d4f235680c3bec, at pixel box left 2, top 2, right 762, bottom 617 with Pillow, then saved as JPEG quality 90 without metadata. Output sha256 c277f4fe08c0a4efa3305ad39ea5d8bedbdb4735adac116924280e27b3c9206a. No color change, no annotation, and no other edit.
dermoscopy · CC BY 4.0 · Isabela Boechat Morato and coauthors

File: assets/media/cases/case-43-dermoscopy.jpg

Source: Morato IB, Gontijo JRV, Tavares GT, Bittencourt FV. Anais Brasileiros de Dermatologia 2022, via PubMed Central (PMC9263629)

Morato and coauthors, Anais Brasileiros de Dermatologia 2022, Figure 2 panel B, doi:10.1016/j.abd.2021.02.012. CC BY 4.0. Cropped from the composite figure by Docutis.

Modification: cropped — Panel B of Figure 2 was cropped from the figure image embedded on page 2 of the article PDF in the PMC open-access package PMC9263629 (PDF image object 5, 1505 x 1312 pixels), source sha256 dcdbf421339af5fedce5254f23551450d07a3b4df57f9d1ce3d4f235680c3bec, at pixel box left 783, top 2, right 1503, bottom 617 with Pillow, then saved as JPEG quality 90 without metadata. Output sha256 c047e868ca0c602391acbfe16b9c07939d5d1927265c260f509ac743273ac89e. No color change, no annotation, and no other edit.

Observations

A child's toes. A faint brown band runs along one side of the nail of the second toe.
A brown band occupies one side of the nail plate. Inside it, longitudinal lines of light and dark brown vary in shade and thickness, and the band edge facing the plate centre is blurred. Dark pigment runs along the proximal edge of the plate. Air bubbles and a fluid edge cross the field.

Observation prompts

Do the lines inside the band have the same shade and thickness?
Is pigment visible on the skin around the nail, or only at the plate edge?

Features, certainty, and weight

Clinical morphology, dermoscopic structure, and image context are separate. An image mark does not compete with a diagnostic structure.

Clinical morphology

None stored on this case.

Dermoscopic structure

Brown longitudinal lines of uneven shade — Probably present; Major clue

Lines of light and dark brown vary in shade and thickness inside a one-sided band. Their irregularity is clear in parts and soft in others, so the certainty is probable.

Canonical pattern: longitudinal-nail-plate-lines. Educational role: Diagnostic structure. Case certainty and weight stay on this case.

Case-specific observation

Dark pigment at the proximal plate edge — Uncertain; Weak

Dark pigment lines the proximal edge. Fold skin and cuticle cannot be separated here, so no Hutchinson sign is claimed.

Canonical pattern: not linked. Dark pigment at the proximal plate edge cannot be placed on fold skin or under the cuticle in this frame. The source's Hutchinson sign is not encoded, so it stays case-specific and uncertain.

Context and image information

None stored on this case.

Differential

Junctional melanocytic nevus of the nail unit

Why it fits: Brown band with longitudinal lines.; A child.; The case text reports histopathology.

Why not: Line irregularity and a blurred edge.

The source states that irregular features are common in benign childhood bands.
Nail-unit melanoma

Why it fits: Irregular line shade and thickness, blurred edge.

Why not: Melanoma is extremely rare in children according to the source.; The plate is intact.

The same features would weigh more in an adult.
Subungual haemorrhage

Why it fits: Dark colour in a nail.

Why not: The colour is brown in longitudinal lines, not red to black spots.

Blood does not form a longitudinal brown band.

Closest mimic

Nail-unit melanoma

Irregular longitudinal lines and a blurred edge are warning features in adults.

Why not

Nail-unit melanoma — The adult nail melanoma also shows irregular lines but with a fissured plate. Here the plate is intact and the patient is a child.
Subungual haemorrhage — Blood forms red to black spots, not a longitudinal brown band.

Reasoning

The case text reports a junctional melanocytic nevus on biopsy after these first-consultation images. The dermoscopic frame shows a one-sided brown band with lines of uneven shade and a blurred edge.

Uneven lines are probably visible and are the major finding; in a child the source says they are common in benign bands. The proximal pigment is uncertain and weak. The lesion-specific histopathology sentence is the confirmation.

Diagnostic trap

Applying adult melanonychia warning rules unchanged to a child, or claiming a Hutchinson sign from pigment at the plate edge.

Mentor note

This is the narrower benign childhood band. Compare it with the adult great-toenail case, where irregular lines come with a broken plate.

Take-home rule

In a child, irregular band features are common and are weighed with age. The decision to biopsy remains individual.

Management brief

No management category is stored. The source history is not a Docutis recommendation. This brief is not a protocol and remains review required.

A broad dark band on a child's fingernail (case-g26-06)

Teaching type: Reasoning case
Curriculum level: 4 · mimic
Skills: Pigmented nail band, Evidence weighting
Recorded diagnosis: Recurrent junctional melanocytic nevus of the nail unit
Disease record: melanocytic-nevus
Confirmation: histopathology — Morato and coauthors (Anais Brasileiros de Dermatologia 2022, doi:10.1016/j.abd.2021.02.012), checked 2026-10-02, report for Case 3 a biopsy one year earlier compatible with a junctional melanocytic nevus, regrowth since then, and a second evaluation of the histopathology without signs of malignancy. The photographs show the regrown band, so the histopathology predates these frames. The band stayed stable for two years.
Site: Fifth left finger, nail unit

Provenance

clinical · CC BY 4.0 · Isabela Boechat Morato and coauthors

File: assets/media/cases/case-44-clinical.jpg

Source: Morato IB, Gontijo JRV, Tavares GT, Bittencourt FV. Anais Brasileiros de Dermatologia 2022, via PubMed Central (PMC9263629)

Morato and coauthors, Anais Brasileiros de Dermatologia 2022, Figure 3 panel A, doi:10.1016/j.abd.2021.02.012. CC BY 4.0. Cropped from the composite figure by Docutis.

Modification: cropped — Panel A of Figure 3 was cropped from the figure image embedded on page 2 of the article PDF in the PMC open-access package PMC9263629 (PDF image object 6, 1505 x 834 pixels), source sha256 ce36b982a3dd2acaad68a6481a6453b3a1ed430c017994b63d3f23476d7391ae, at pixel box left 2, top 0, right 789, bottom 832 with Pillow, then saved as JPEG quality 90 without metadata. Output sha256 c41e90570e8a40bf952b9d1745e051ab5027a3d9103539636da72d121117a787. No color change, no annotation, and no other edit.
dermoscopy · CC BY 4.0 · Isabela Boechat Morato and coauthors

File: assets/media/cases/case-44-dermoscopy.jpg

Source: Morato IB, Gontijo JRV, Tavares GT, Bittencourt FV. Anais Brasileiros de Dermatologia 2022, via PubMed Central (PMC9263629)

Morato and coauthors, Anais Brasileiros de Dermatologia 2022, Figure 3 panel B, doi:10.1016/j.abd.2021.02.012. CC BY 4.0. Cropped from the composite figure by Docutis.

Modification: cropped — Panel B of Figure 3 was cropped from the figure image embedded on page 2 of the article PDF in the PMC open-access package PMC9263629 (PDF image object 6, 1505 x 834 pixels), source sha256 ce36b982a3dd2acaad68a6481a6453b3a1ed430c017994b63d3f23476d7391ae, at pixel box left 797, top 0, right 1503, bottom 832 with Pillow, then saved as JPEG quality 90 without metadata. Output sha256 edb7f2858a90556950d1415093dc862990d355223cfa00c771eec3ffc72b1c7d. No color change, no annotation, and no other edit.

Observations

A child's finger with a broad black-brown band running the full length of the nail.
A broad band of dark brown to black longitudinal lines fills the central part of the plate. The lines differ in darkness and thickness, and the band edges are slightly blurred. The plate surface is intact. Grey shading lies at the proximal edge under the cuticle.

Observation prompts

How do the lines differ in darkness and thickness?
Is the nail plate surface intact or broken?

Features, certainty, and weight

Clinical morphology, dermoscopic structure, and image context are separate. An image mark does not compete with a diagnostic structure.

Clinical morphology

Broken or missing nail plate — Not visible in this image; Supportive

The plate surface is intact. No break or debris is visible.

Canonical pattern: nail-plate-destruction. Educational role: Diagnostic structure. Case certainty and weight stay on this case.

Dermoscopic structure

Broad band of dark lines of differing thickness — Clearly visible; Major clue

Dark brown to black longitudinal lines differ clearly in darkness and thickness across a broad band.

Canonical pattern: longitudinal-nail-plate-lines. Educational role: Diagnostic structure. Case certainty and weight stay on this case.

Case-specific observation

None stored on this case.

Context and image information

None stored on this case.

Differential

Recurrent junctional melanocytic nevus of the nail unit

Why it fits: Broad band of longitudinal lines in a child.; The case text reports histopathology and a second review.

Why not: The histopathology predates these photographs.

The diagnosis rests on an earlier biopsy of the same band and its re-review.
Nail-unit melanoma

Why it fits: Broad dark band with lines of differing thickness.

Why not: A small child.; Intact plate.; Re-reviewed histopathology without malignancy.

In an adult this frame would weigh much more heavily.
Subungual haemorrhage

Why it fits: Dark colour under a nail.

Why not: Regular longitudinal lines, not red to black spots.

Blood does not make a broad band of lines.

Closest mimic

Nail-unit melanoma

A broad dark band with lines of differing thickness is an adult warning look.

Why not

Nail-unit melanoma — The adult nail melanoma shows irregular lines with a fissured plate and debris. Here the plate is intact and the patient is three years old.
Subungual haemorrhage — Blood forms red to black spots, not a broad band of longitudinal lines.

Reasoning

The case text reports a junctional melanocytic nevus on an earlier biopsy of this band, with regrowth and a re-review without malignancy. The dermoscopic frame shows a broad band of dark lines of differing thickness on an intact plate.

The irregular lines are clearly visible and are the major finding; the source says they are common in benign childhood bands. The intact plate supports the benign reading. The histopathology predates the photographs, which weakens the confirmation.

Diagnostic trap

Using line irregularity alone to call a childhood band malignant, or using this benign result to dismiss an adult band.

Mentor note

This dramatic childhood band shares irregular lines with the adult nail melanoma. The plate damage and the age differ.

Take-home rule

Irregular nail lines are weighed with age and plate integrity. In children they are common in benign bands, and the decision remains individual.

Management brief

No management category is stored. The source history is not a Docutis recommendation. This brief is not a protocol and remains review required.

A discoloured great toenail with a split (case-g26-07)

Teaching type: Reasoning case
Curriculum level: 4 · melanoma
Skills: Pigmented nail band, Nail-unit damage
Recorded diagnosis: Nail-unit melanoma
Disease record: acral-melanoma
Confirmation: clinical_diagnosis — The Figure 1 caption of Dika and coauthors (Journal of Clinical Medicine 2021, doi:10.3390/jcm10030478), checked 2026-10-02, names a nail melanoma of the great toenail with irregular longitudinal bands, plate dystrophy, and pigmentation reaching the hyponychium. The article does not state histopathology for this figure, so confirmation stays at the caption.
Site: Great toe, nail unit

Provenance

clinical · CC BY 4.0 · Emi Dika and coauthors

File: assets/media/cases/case-45-clinical.jpg

Source: Dika E, Lambertini M, Pellegrini C, Veronesi G, Melotti B, Riefolo M, Sperandi F, Patrizi A, et al. Journal of Clinical Medicine 2021, via PubMed Central (PMC7866093)

Dika and coauthors, Journal of Clinical Medicine 2021, Figure 1 panel a, doi:10.3390/jcm10030478. CC BY 4.0. Cropped from the composite figure by Docutis.

Modification: cropped — Panel a of Figure 1 was cropped from the figure image embedded on page 2 of the article PDF in the PMC open-access package PMC7866093 (PDF image object 88, 1662 x 735 pixels), source sha256 32fb60b69752b797857247679fa56971e7142a7d64cf1d41d9a499534d2a27f0, at pixel box left 0, top 0, right 827, bottom 735 with Pillow, then saved as JPEG quality 90 without metadata. Output sha256 79a3a39aaa1ee4db981955dd01c77777dd3158270fe265e24d3122bf2d77f9a6. No color change, no annotation, and no other edit.
dermoscopy · CC BY 4.0 · Emi Dika and coauthors

File: assets/media/cases/case-45-dermoscopy.jpg

Source: Dika E, Lambertini M, Pellegrini C, Veronesi G, Melotti B, Riefolo M, Sperandi F, Patrizi A, et al. Journal of Clinical Medicine 2021, via PubMed Central (PMC7866093)

Dika and coauthors, Journal of Clinical Medicine 2021, Figure 1 panel b, doi:10.3390/jcm10030478. CC BY 4.0. Cropped from the composite figure by Docutis.

Modification: cropped — Panel b of Figure 1 was cropped from the figure image embedded on page 2 of the article PDF in the PMC open-access package PMC7866093 (PDF image object 88, 1662 x 735 pixels), source sha256 32fb60b69752b797857247679fa56971e7142a7d64cf1d41d9a499534d2a27f0, at pixel box left 829, top 0, right 1662, bottom 735 with Pillow, then saved as JPEG quality 90 without metadata. Output sha256 92921d5333fe94744054c4328107676cf4c319d66ead5caf98505ed1a66a23cf. No color change, no annotation, and no other edit.

Observations

A great toenail with brown-grey discolouration across the plate and a longitudinal split through its middle.
Longitudinal bands of yellow-brown, orange-brown, and dark brown cross the whole plate and differ in width and colour. A central longitudinal fissure contains white scale and black-brown dots. Faint brownish colour lies on the skin below the free edge.

Observation prompts

Do the bands differ in width and colour?
Is the nail plate intact, or split?

Features, certainty, and weight

Clinical morphology, dermoscopic structure, and image context are separate. An image mark does not compete with a diagnostic structure.

Clinical morphology

Fissured plate with dark dots — Clearly visible; Major clue

A central longitudinal fissure with white scale and black-brown dots breaks the plate.

Canonical pattern: nail-plate-destruction. Educational role: Diagnostic structure. Case certainty and weight stay on this case.

Dermoscopic structure

Bands of differing width and colour across the plate — Clearly visible; Major clue

Yellow-brown, orange-brown, and dark brown bands run lengthwise and differ clearly in width and colour.

Canonical pattern: longitudinal-nail-plate-lines. Educational role: Diagnostic structure. Case certainty and weight stay on this case.

Case-specific observation

Colour on the skin below the free edge — Uncertain; Weak

Faint brownish colour lies below the free edge. It is not clear enough to call periungual pigment.

Canonical pattern: not linked. Faint colour below the free edge is not clear enough to call periungual pigment. The caption's Hutchinson sign is not encoded.

Context and image information

None stored on this case.

Differential

Nail-unit melanoma

Why it fits: Irregular longitudinal bands across the plate.; Fissured plate with dark dots.

Why not: No histopathology statement in the source.

Irregular bands plus plate damage carry the concern; the caption is the label.
Subungual haemorrhage

Why it fits: Dark dots in the plate.

Why not: Most of the colour is brown and banded lengthwise, not red to black spots.

Ronger and coauthors caution that blood spots do not exclude melanoma.
Onychomycosis

Why it fits: Yellow discolouration and a split plate.

Why not: Dark brown longitudinal bands are present.

Fungus can coexist and can mimic; it does not explain the bands.

Closest mimic

Subungual haemorrhage

Dark dots in a damaged toenail can be blood.

Why not

Subungual haemorrhage — Most of the colour is brown and banded lengthwise. Blood spots in a nail do not exclude melanoma.
Junctional melanocytic nevus of the nail unit — The childhood bands share irregular lines but have an intact plate. This adult plate is fissured.

Reasoning

The source caption names this great-toenail lesion a nail melanoma. The dermoscopic frame shows irregular longitudinal bands across the plate and a fissure with dark dots. No histopathology is stated.

Irregular bands and the fissured plate are clearly visible and are the major clues. Colour below the free edge is uncertain and weak. The confirmation is a peer-reviewed caption, not histopathology.

Diagnostic trap

Blaming fungus or trauma for a banded damaged toenail, or claiming a Hutchinson sign from a faint shadow.

Mentor note

This adult nail shares irregular lines with the childhood bands. Plate damage, whole-plate involvement, and age differ.

Take-home rule

In an adult, irregular longitudinal bands with plate damage need a melanoma differential and usually histopathology.

Management brief

No management category is stored. The source history is not a Docutis recommendation. This brief is not a protocol and remains review required.

A cluster of small brown spots on the sole (case-g27-01)

Teaching type: Teaching case
Curriculum level: 3 · mimic
Skills: Furrow or ridge, Many flat brown macules
Recorded diagnosis: Acquired agminated melanocytic nevi of the sole
Disease record: melanocytic-nevus
Confirmation: histopathology — Terada and coauthors (JAAD Case Reports 2026, doi:10.1016/j.jdcr.2026.05.048), checked 2026-10-02, report histopathology of a biopsy of one spot of this cluster at age 46 showing junctional melanocytes without nuclear atypia and sparse PRAME staining, supporting benign nevi, and no melanoma over nine years of follow-up. The biopsy was taken seven years after these photographs and sampled one spot of the cluster, so it does not verify the photographed spots one by one. The source's printed panel letters for the later visits do not match its caption; only the first-visit panels, which agree, were used.
Site: Right sole, plantar

Provenance

clinical · CC BY 4.0 · Akari Terada and coauthors

File: assets/media/cases/case-46-clinical.jpg

Source: Terada A, Rokunohe D, Sawamura D, Akasaka E. JAAD Case Reports 2026, via PubMed Central (PMC13319713)

Terada and coauthors, JAAD Case Reports 2026, Figure 1 panel B, doi:10.1016/j.jdcr.2026.05.048. CC BY 4.0. Cropped from the composite figure by Docutis.

Modification: cropped — Panel B of Figure 1 was cropped from the figure image embedded on page 2 of the article PDF in the PMC open-access package PMC13319713.1 (PDF image object 7, 1943 x 889 pixels, stored losslessly in the PDF), source sha256 4308a4d348806e77fdbba45f93fbbe4f94294cb97a41bfc001446ddd8d5eb90f computed over the decoded RGB pixel buffer because PDF image extractors re-encode the file differently (article PDF sha256 a0347363234690dd82b442740f92a7c60b35fd9297f38e4a4f9cfb424b8967dc), at pixel box left 508, top 67, right 942, bottom 397 with Pillow, then saved as JPEG quality 90 without metadata. Output sha256 8b01b7f606704b4c053e1bd86a9cd13c3ac7fcc5867fdc2febdc63aa383c8fd2. No color change, no annotation, and no other edit.
dermoscopy · CC BY 4.0 · Akari Terada and coauthors

File: assets/media/cases/case-46-dermoscopy.jpg

Source: Terada A, Rokunohe D, Sawamura D, Akasaka E. JAAD Case Reports 2026, via PubMed Central (PMC13319713)

Terada and coauthors, JAAD Case Reports 2026, Figure 2 panel A, doi:10.1016/j.jdcr.2026.05.048. CC BY 4.0. Cropped from the composite figure by Docutis.

Modification: cropped — Panel A of Figure 2 was cropped from the figure image embedded on page 2 of the article PDF in the PMC open-access package PMC13319713.1 (PDF image object 13, 1494 x 868 pixels, stored losslessly in the PDF), source sha256 aa7dc38a729d963c2629bc31c8dd60e659658eccf470b546a86998f7ca9d1174 computed over the decoded RGB pixel buffer because PDF image extractors re-encode the file differently (article PDF sha256 a0347363234690dd82b442740f92a7c60b35fd9297f38e4a4f9cfb424b8967dc), at pixel box left 2, top 23, right 723, bottom 865 with Pillow, then saved as JPEG quality 90 without metadata. Output sha256 0c4fc37824037ad0647b298c4f0c6c25ad7cb6152db62ca738e7e0f78bb55a84. No color change, no annotation, and no other edit.

Observations

A cluster of many small brown macules, one to a few millimetres each, sits in one area of the sole. Some macules are darker than others. The skin markings run across the cluster.
Several separate tan-brown spots. In each spot, thin dark brown lines run along the skin markings, with broader pale tan bands between them. Fine short cross-lines join some lines. No broad dark bands, no blotch, and no dots off the lines are present. Sweat-duct openings are not resolved.

Observation prompts

Are the brown lines thinner or wider than the pale bands between them?
Does every spot show the same line arrangement?

Features, certainty, and weight

Clinical morphology, dermoscopic structure, and image context are separate. An image mark does not compete with a diagnostic structure.

Clinical morphology

Many small flat brown macules in one area — Clearly visible; Supportive

Many separate small brown macules are grouped in one area of the sole.

Canonical pattern: flat-brown-macule. Educational role: Descriptive morphology, not a dermoscopic structure. Case certainty and weight stay on this case.

Dermoscopic structure

Thin pigmented lines with broader pale bands — Probably present; Major clue

In each spot the brown lines are thin and the pale bands between them are broader, which favors pigment in the furrows. Sweat-duct openings are not resolved, so the certainty stays probable.

Canonical pattern: parallel-furrow-pattern. Educational role: Diagnostic structure. Case certainty and weight stay on this case.
Broad parallel pigmented bands — Not visible in this image; Supportive

No broad brown bands with thin pale lines are visible in any spot.

Canonical pattern: parallel-ridge-pattern. Educational role: Diagnostic structure. Case certainty and weight stay on this case.

Case-specific observation

None stored on this case.

Context and image information

None stored on this case.

Differential

Acquired agminated melanocytic nevi of the sole

Why it fits: Thin lines with broader pale bands in each spot.; The case text reports benign histopathology and long follow-up.

Why not: The cluster as a whole looked atypical to the source authors.; The biopsy came after these frames.

Each spot is read on its own; the source biopsied one spot because the whole cluster looked atypical.
Acral melanoma

Why it fits: Many new spots appeared in adulthood.; The cluster has uneven darkness.

Why not: No broad ridge-type bands, no blotch, no irregular dots in these frames.

New acral pigment in an adult keeps melanoma in the differential; these frames show a furrow-type pattern in every spot.
Speckled lentiginous nevus

Why it fits: Several darker spots grouped in one area.

Why not: No tan background patch is visible between the spots.

The source reports no background pigmented macule.

Closest mimic

Acral melanoma

New pigmented spots on the sole of an adult, with uneven darkness across the cluster, keep melanoma in mind.

Why not

Acral melanoma — No spot shows broad ridge-type bands, a blotch, or irregular dots. New spots in an adult still need follow-up, as the source did.
Speckled lentiginous nevus — No tan background patch joins the spots in these frames.

Reasoning

The source reports benign histopathology from one spot of this sole cluster, taken seven years after these frames, and no melanoma over nine years. The dermoscopic frame shows thin lines with broader pale bands in every spot, without ridge-type bands or a blotch.

The furrow-type width geometry is probably visible and is the major clue. The absent ridge bands support it. The confirmation is a later biopsy of one spot plus long follow-up, which is weaker than same-day histopathology of the photographed spot.

Diagnostic trap

Calling every pattern of parallel lines on the sole benign, or letting a benign cluster clear a single new acral lesion elsewhere.

Mentor note

This is the first benign acral case in Docutis whose thin lines sit in the furrows by width. Compare it with the heel lesions whose broad bands sit on the ridges.

Take-home rule

On the sole, thin pigmented lines with broader pale bands are a furrow-type pattern that supports a benign reading in this frame. It is weighed with the rest of the lesion and is not a clearance.

Management brief

No management category is stored. The source history is not a Docutis recommendation. This brief is not a protocol and remains review required.

A small dark spot on the sole (case-g27-02)

Teaching type: Teaching case
Curriculum level: 3 · mimic
Skills: Furrow or ridge
Recorded diagnosis: Acral melanocytic nevus
Disease record: melanocytic-nevus
Confirmation: clinical_diagnosis — Figure 1 of Erol Mart and coauthors (International Journal of Dermatology 2026, doi:10.1111/ijd.70384), checked 2026-10-02, is titled acral nevus on the left plantar surface. The methods and limitations state that nevi were not confirmed by histopathology: they were included after a stable clinical course of at least five years and dermoscopic features consistent with benign acral patterns. A benign dermoscopic pattern was therefore part of the inclusion rule, so the diagnosis is not independent of the pattern taught here. The authors note a residual risk of misclassification.
Site: Left plantar sole

Provenance

clinical · CC BY 4.0 · Handan Merve Erol Mart and coauthors

File: assets/media/cases/case-47-clinical.jpg

Source: Erol Mart HM, Aydemir AT, Pietkiewicz P, Akay BN. International Journal of Dermatology 2026, via PubMed Central (PMC13342755)

Erol Mart and coauthors, International Journal of Dermatology 2026, Figure 1 panel a, doi:10.1111/ijd.70384. CC BY 4.0. Cropped from the composite figure by Docutis.

Modification: cropped — Panel a of Figure 1 was cropped from the figure image embedded on page 4 of the article PDF in the PMC open-access package PMC13342755.1 (PDF image object 7, 2079 x 1220 pixels), source sha256 90f0e933dd8efb7c40f078d9085afc778358a581d55529e3cc6f9a23ef698141, at pixel box left 0, top 0, right 792, bottom 1220 with Pillow, then saved as JPEG quality 90 without metadata. Output sha256 e93fa6a9d5e940419cef57bbf07a4eae9b4e96be831a65fd94ebe7e64aa2d1df. No color change, no annotation, and no other edit.
dermoscopy · CC BY 4.0 · Handan Merve Erol Mart and coauthors

File: assets/media/cases/case-47-dermoscopy.jpg

Source: Erol Mart HM, Aydemir AT, Pietkiewicz P, Akay BN. International Journal of Dermatology 2026, via PubMed Central (PMC13342755)

Erol Mart and coauthors, International Journal of Dermatology 2026, Figure 1 panel b, doi:10.1111/ijd.70384. CC BY 4.0. Cropped from the composite figure by Docutis.

Modification: cropped — Panel b of Figure 1 was cropped from the figure image embedded on page 4 of the article PDF in the PMC open-access package PMC13342755.1 (PDF image object 7, 2079 x 1220 pixels), source sha256 90f0e933dd8efb7c40f078d9085afc778358a581d55529e3cc6f9a23ef698141, at pixel box left 797, top 0, right 1464, bottom 614 with Pillow, then saved as JPEG quality 90 without metadata. Output sha256 ce47bbab4d3a31f1ae4913c4e5174ab0edc40786d9ee941547e284b8b1683de9. No color change, no annotation, and no other edit.

Observations

A hand holds a bare sole. A small dark brown macule sits in the middle of the sole among the skin creases.
Brown pigment forms thin parallel dotted lines with pale bands between them, plus many small dark brown dots and globules along the lines and at the edge. The lines are thinner than or as wide as the pale bands. No broad dark bands and no blotch are present. Faint white dots in rows are visible only on the surrounding skin.

Observation prompts

Are the brown lines thinner or wider than the pale bands?
Do the dark dots follow the lines or scatter at random?

Features, certainty, and weight

Clinical morphology, dermoscopic structure, and image context are separate. An image mark does not compete with a diagnostic structure.

Clinical morphology

None stored on this case.

Dermoscopic structure

Thin dotted parallel lines with pale bands — Probably present; Major clue

Thin dotted brown lines run in parallel with pale bands at least as wide between them, which favors pigment in the furrows. Pores are not resolved inside the lesion in this panel, so the certainty stays probable.

Canonical pattern: parallel-furrow-pattern. Educational role: Diagnostic structure. Case certainty and weight stay on this case.
Broad parallel pigmented bands — Not visible in this image; Supportive

No broad brown bands with thin pale lines are visible.

Canonical pattern: parallel-ridge-pattern. Educational role: Diagnostic structure. Case certainty and weight stay on this case.

Case-specific observation

Many small dark dots and globules — Clearly visible; Weak

Many small dark brown dots and globules sit along the lines and at the edge.

Canonical pattern: not linked. Small dark dots and globules are clearly visible along the lines. A reusable dots-and-globules pattern stays deferred, as in Goal 25, rather than created from case-specific dots.

Context and image information

None stored on this case.

Differential

Acral melanocytic nevus

Why it fits: Thin parallel dotted lines with pale bands at least as wide.; No blotch.

Why not: No histopathology; verification is follow-up stability.

The source label rests on at least five years of stability plus a benign pattern.
Acral melanoma

Why it fits: Many dark dots and globules.; More than one shade of brown.

Why not: No broad ridge-type bands.; No blotch.

Dots and globules alone do not make the pattern malignant; their arrangement along thin lines matters.
Subcorneal haematoma

Why it fits: A dark spot on the sole.

Why not: The colour is brown and organized in lines, not red to maroon and structureless.

Blood colour is read under the dermatoscope.

Closest mimic

Acral melanoma

The heel lesion from the same study, photographed with the same device, shows broad bands on the ridges.

Why not

Acral melanoma — The heel lesion from the same study shows broad bands with thin pale lines. Here the lines are thin. That supports the source label in this frame; it is not a rule.
Subcorneal haematoma — The colour is brown and arranged in lines, not red to maroon and structureless.

Reasoning

The source titles this plantar lesion an acral nevus, verified by at least five years of stability rather than histopathology. The dermoscopic frame shows thin dotted parallel lines with pale bands at least as wide and many small dots, without ridge-type bands or a blotch.

The furrow-type width geometry is probably visible and is the major clue. The missing ridge bands support it. The dots are clearly visible but weak on their own. The verification is follow-up stability that partly depended on this same pattern, so it is weaker than histopathology.

Diagnostic trap

Reading many dark dots as a malignant clue without asking whether they follow thin lines, or treating a follow-up label as if it were histopathology.

Mentor note

This nevus comes from the same study and device as the heel lesion with broad ridge bands. Put the two dermoscopic frames side by side and compare line width.

Take-home rule

Thin pigmented lines with pale bands at least as wide are a furrow-type pattern. Keep the verification strength in view: stability is not histopathology.

Management brief

No management category is stored. The source history is not a Docutis recommendation. This brief is not a protocol and remains review required.

A large dark patch on the outer heel (case-g27-03)

Teaching type: Teaching case
Curriculum level: 3 · melanoma
Skills: Furrow or ridge, Acral pigment
Recorded diagnosis: Acral melanoma in situ
Disease record: acral-melanoma
Confirmation: histopathology — The Figure 5 caption of Park and Yun (Dermatopathology 2022, doi:10.3390/dermatopathology9030035), checked 2026-10-02, describes one acral melanoma in situ in a 68-year-old woman with the clinical image (A), dermoscopy (B), a skin biopsy (C), and Melan-A immunostaining of a lentiginous proliferation of atypical melanocytes (D). The histopathology panels were not stored. The caption does not give a biopsy date relative to the photographs.
Site: Outer heel, plantar sole

Provenance

clinical · CC BY 4.0 · Sanghyun Park and Sook Jung Yun

File: assets/media/cases/case-48-clinical.jpg

Source: Park S, Yun SJ. Dermatopathology 2022, via PubMed Central (PMC9397077)

Park and Yun, Dermatopathology 2022, Figure 5 panel A, doi:10.3390/dermatopathology9030035. CC BY 4.0. Cropped from the composite figure by Docutis.

Modification: cropped — Panel A of Figure 5 was cropped from the figure image embedded on page 6 of the article PDF in the PMC open-access package PMC9397077.1 (PDF image object 147, 961 x 704 pixels), source sha256 072fcd94c832e00dd3d710218754b892be37c9baffed4d290f92ce77de9a7aa6, at pixel box left 12, top 11, right 469, bottom 334 with Pillow, then saved as JPEG quality 90 without metadata. Output sha256 2308ceba04a7b7b4a105142de93ee4d7b1cef5f5e91a0714a971b4f997a3bc6a. No color change, no annotation, and no other edit.
dermoscopy · CC BY 4.0 · Sanghyun Park and Sook Jung Yun

File: assets/media/cases/case-48-dermoscopy.jpg

Source: Park S, Yun SJ. Dermatopathology 2022, via PubMed Central (PMC9397077)

Park and Yun, Dermatopathology 2022, Figure 5 panel B, doi:10.3390/dermatopathology9030035. CC BY 4.0. Cropped from the composite figure by Docutis.

Modification: cropped — Panel B of Figure 5 was cropped from the figure image embedded on page 6 of the article PDF in the PMC open-access package PMC9397077.1 (PDF image object 147, 961 x 704 pixels), source sha256 072fcd94c832e00dd3d710218754b892be37c9baffed4d290f92ce77de9a7aa6, at pixel box left 479, top 11, right 946, bottom 334 with Pillow, then saved as JPEG quality 90 without metadata. Output sha256 163477d47bc1a2ee5da729a2bc00ebe5bd20a58f3f3407bd05c02292ff440544. No color change, no annotation, and no other edit.

Observations

A large dark brown to black patch with an uneven outline sits on the outer heel. Its colour is darker in some parts than others.
Thin white scale lines run in parallel across the field. The brown pigment fills the broad bands between those white lines, darker in some zones and lighter in others. A printed millimetre scale is at the lower edge. A thin straight horizontal line crosses the frame.

Observation prompts

Where does the white scale sit, and where does the brown pigment sit?
Are the brown bands broader or thinner than the pale lines?

Features, certainty, and weight

Clinical morphology, dermoscopic structure, and image context are separate. An image mark does not compete with a diagnostic structure.

Clinical morphology

Large dark patch with an uneven outline — Clearly visible; Supportive

A large dark brown to black patch with an uneven outline and uneven colour.

Canonical pattern: irregular-brown-patch. Educational role: Descriptive morphology, not a dermoscopic structure. Case certainty and weight stay on this case.

Dermoscopic structure

Brown pigment in broad bands between white furrow lines — Probably present; Major clue

Thin white scale lines mark the furrows and the brown pigment fills the broad bands between them, which favors pigment on the ridges. Pores are not resolved, so the certainty stays probable.

Canonical pattern: parallel-ridge-pattern. Educational role: Diagnostic structure. Case certainty and weight stay on this case.
Thin pigmented lines with broader pale bands — Not visible in this image; Supportive

The thin lines in this frame are white scale, not brown pigment. Thin brown furrow lines are not visible.

Canonical pattern: parallel-furrow-pattern. Educational role: Diagnostic structure. Case certainty and weight stay on this case.
Uneven brown with darker zones — Probably present; Supportive

The brown is darker in some zones and lighter in others, without a regular arrangement of shades.

Canonical pattern: irregular-acral-pigmentation. Educational role: Diagnostic structure. Case certainty and weight stay on this case.

Case-specific observation

Thin straight line across the figure — Clearly visible; Conflicts with a simple reading

A thin straight horizontal line crosses both source panels at the same height. It is part of the source figure, not skin.

Canonical pattern: not linked. A thin straight line in the source figure crosses both panels. It is a one-off figure mark, so it stays case-specific rather than a new artifact id.

Context and image information

Printed millimetre scale — Clearly visible; Conflicts with a simple reading

A printed scale lies at the lower edge of the dermoscopic field. It is not skin.

Canonical pattern: measuring-scale-in-frame. Educational role: Image mark, not a skin finding. Case certainty and weight stay on this case.

Differential

Acral melanoma in situ

Why it fits: Brown pigment in broad bands between thin white furrow lines.; Large patch with uneven colour.

Why not: Not recorded

The figure caption gives a lesion-specific histopathology result.
Acral melanocytic nevus

Why it fits: Flat brown pigment in parallel lines on the sole.

Why not: The pigment fills the broad bands, not thin lines.; Large size and uneven colour.

A typical acral nevus places thin pigmented lines in the furrows.
Subcorneal haematoma

Why it fits: A dark patch on the heel.

Why not: The colour is brown and banded, not red to maroon and structureless.

Blood can follow ridges too, so colour is read first.

Closest mimic

Acral melanocytic nevus

Parallel brown lines on the sole are a common benign look. The difference is where the pigment sits.

Why not

Acral melanocytic nevus — The brown fills the broad bands between the white furrow lines rather than sitting in thin lines. That raises concern; it is not proof on its own.
Subcorneal haematoma — The colour is brown in bands, not red to maroon and structureless.

Reasoning

The source figure gives a lesion-specific histopathology result of melanoma in situ for this outer-heel patch. The dermoscopic frame shows brown pigment in broad bands between thin white furrow lines, a ridge-type geometry.

The ridge-type placement is probably visible and is the major clue. The uneven brown and the large uneven patch support concern. The scale and the straight line conflict only if read as skin. The figure-caption histopathology is the confirmation.

Diagnostic trap

Mistaking the white scale lines for the pigment pattern, or calling ridge versus furrow from the diagnosis rather than from where the pigment sits.

Mentor note

This is the second independent parallel ridge example in Docutis, in another patient and another source. Here the white scale in the furrows does the work that pores do elsewhere.

Take-home rule

On the sole, find a furrow marker first, scale or pores. Brown pigment in the broad bands between furrows is a ridge-type pattern and needs a melanoma differential.

Management brief

No management category is stored. The source history is not a Docutis recommendation. This brief is not a protocol and remains review required.

A brown oval patch at the base of a finger (case-g27-04)

Teaching type: Expert-challenge case
Curriculum level: 5 · melanoma
Skills: Furrow or ridge, Evidence weighting
Recorded diagnosis: Acral lentiginous melanoma in situ
Disease record: acral-melanoma
Confirmation: histopathology — Money and coauthors (JAAD Case Reports 2024, doi:10.1016/j.jdcr.2024.09.025), checked 2026-10-02, report that histopathologic examination showed increased single atypical melanocytes with prominent dendrites and increased mitoses, confirming acral lentiginous melanoma in situ, in a single-lesion case report. The histopathology figures were not stored.
Site: Palmar crease of the left fifth digit, palm side

Provenance

clinical · CC BY 4.0 · Silas M Money and coauthors

File: assets/media/cases/case-49-clinical.jpg

Source: Money SM, Davis LS, Rabinovitz HS, Powell MR, Buchanan KL. JAAD Case Reports 2024, via PubMed Central (PMC11626072)

Money and coauthors, JAAD Case Reports 2024, Figure 1 panel B, doi:10.1016/j.jdcr.2024.09.025. CC BY 4.0. Cropped from the composite figure by Docutis.

Modification: cropped — Panel B of Figure 1 was cropped from the figure image embedded on page 2 of the article PDF in the PMC open-access package PMC11626072.1 (PDF image object 6, 1495 x 1006 pixels), source sha256 dc0d25f7d6d4cfbaf9c9150cfbccc5db57063a73d0f444fb7df59a1a361f2ee0, at pixel box left 783, top 3, right 1490, bottom 1002 with Pillow, then saved as JPEG quality 90 without metadata. Output sha256 f3b27e253a8661397a4bfee02d3c9871481d89aef45ed8425de248493e818c6b. No color change, no annotation, and no other edit.
dermoscopy · CC BY 4.0 · Silas M Money and coauthors

File: assets/media/cases/case-49-dermoscopy.jpg

Source: Money SM, Davis LS, Rabinovitz HS, Powell MR, Buchanan KL. JAAD Case Reports 2024, via PubMed Central (PMC11626072)

Money and coauthors, JAAD Case Reports 2024, Figure 2 panel A, doi:10.1016/j.jdcr.2024.09.025. CC BY 4.0. Cropped from the composite figure by Docutis.

Modification: cropped — Panel A of Figure 2 was cropped from the figure image embedded on page 2 of the article PDF in the PMC open-access package PMC11626072.1 (PDF image object 7, 1495 x 746 pixels), source sha256 04613e3fe5ad0999e067db7f75a369314a1615505e4481932bb51080655986d3, at pixel box left 0, top 0, right 744, bottom 746 with Pillow, then saved as JPEG quality 90 without metadata. Output sha256 3339d6ff385ea7dd40bd12f875c178ed29ab27e341b7b244fa0cec6e71ea1770. No color change, no annotation, and no other edit.

Observations

A small oval patch of several browns, darker at one end, sits at the base of the little finger on the palm side, along a crease.
Broad pale ridges with rows of small white pore dots run in parallel. Thin brown lines lie between the ridges across most of the lesion. Toward the top, a darker eccentric blotch with criss-crossing lines sits on several shades of brown. Printed red and black arrows and a printed scale with text are in the field.

Observation prompts

Where are the white pore dots, and where are the brown lines?
Is any part of the lesion darker and less orderly than the rest?

Features, certainty, and weight

Clinical morphology, dermoscopic structure, and image context are separate. An image mark does not compete with a diagnostic structure.

Clinical morphology

None stored on this case.

Dermoscopic structure

Thin brown lines in the furrows, pores on the ridges — Clearly visible; Conflicts with a simple reading

White pore dots sit in rows on the broad pale ridges, and thin brown lines lie between them across most of the lesion. Ridge and furrow positions are resolved by the pores.

Canonical pattern: parallel-furrow-pattern. Educational role: Diagnostic structure. Case certainty and weight stay on this case.
Broad parallel pigmented bands — Not visible in this image; Conflicts with a simple reading

No broad brown bands on the ridges are visible; the ridges are pale.

Canonical pattern: parallel-ridge-pattern. Educational role: Diagnostic structure. Case certainty and weight stay on this case.
Eccentric blotch on several browns — Clearly visible; Major clue

A darker eccentric blotch with criss-crossing lines sits at one end, on several shades of brown.

Canonical pattern: irregular-acral-pigmentation. Educational role: Diagnostic structure. Case certainty and weight stay on this case.

Case-specific observation

None stored on this case.

Context and image information

Printed arrows in the dermoscopic field — Clearly visible; Conflicts with a simple reading

Red and black arrows are printed on the source image. They are marks, not skin.

Canonical pattern: printed-pointer. Educational role: Image mark, not a skin finding. Case certainty and weight stay on this case.
Printed scale with text — Clearly visible; Conflicts with a simple reading

A printed millimetre scale with a device name lies across the lower field. It is not skin.

Canonical pattern: measuring-scale-in-frame. Educational role: Image mark, not a skin finding. Case certainty and weight stay on this case.

Differential

Acral lentiginous melanoma in situ

Why it fits: Eccentric blotch.; Several shades of brown.; Recent enlargement and darkening in the source history.

Why not: Most of the lesion shows a furrow pattern.

The case text gives a lesion-specific histopathology result.
Acral melanocytic nevus

Why it fits: Thin brown lines in the furrows, with pores on the ridges.

Why not: Eccentric dark blotch.; Several shades of brown in one lesion.

A furrow pattern is the most common benign acral pattern and still does not outrank a blotch and colour variation.
Acral lentigo

Why it fits: Flat brown palm pigment.

Why not: Eccentric blotch with criss-crossing lines.

Uniform flat pigment would weigh differently from a multicomponent pattern.

Closest mimic

Acral melanocytic nevus

A diffuse furrow pattern is the usual look of a benign acral nevus.

Why not

Acral melanocytic nevus — The furrow pattern fits a nevus, but an eccentric blotch on several browns does not belong to an orderly furrow pattern, and the source reports recent enlargement.
Acral lentigo — The pigment is not uniform; a blotch with criss-crossing lines sits at one end.

Reasoning

The case text gives histopathology of acral lentiginous melanoma in situ for this palm patch. The dermoscopic frame shows a furrow pattern with pores on the ridges across most of the lesion, plus an eccentric blotch on several shades of brown.

The furrow pattern is clearly visible and points the wrong way: it conflicts with the final diagnosis. The eccentric blotch and several browns are clearly visible and carry the concern. The case-text histopathology is the confirmation.

Diagnostic trap

Stopping at a furrow pattern and calling the lesion benign without weighing the blotch, the colours, and the reported enlargement.

Mentor note

This frame shows that a furrow pattern is a weighted clue, not a clearance. Compare it with the benign sole cluster: the same line placement, different company.

Take-home rule

A parallel furrow pattern is the commonest benign acral pattern, not a guarantee. An eccentric blotch, several browns, or reported change still need a melanoma differential.

Management brief

No management category is stored. The source history is not a Docutis recommendation. This brief is not a protocol and remains review required.

A narrow brown band in an adult's fingernail (case-g27-05)

Teaching type: Teaching case
Curriculum level: 3 · mimic
Skills: Pigmented nail band, Nail band and age
Recorded diagnosis: Nail matrix nevus
Disease record: melanocytic-nevus
Confirmation: histopathology — The Figure 2 caption of Park and Yun (Dermatopathology 2022, doi:10.3390/dermatopathology9030035), checked 2026-10-02, describes a nail matrix nevus in a 28-year-old woman with the clinical band (A), regular lines on dermoscopy (B), and junctional nests in the epidermis of the nail matrix on histopathology (C). The histopathology panel was not stored. The caption does not give a biopsy date relative to the photographs.
Site: Fingernail, nail unit

Provenance

clinical · CC BY 4.0 · Sanghyun Park and Sook Jung Yun

File: assets/media/cases/case-50-clinical.jpg

Source: Park S, Yun SJ. Dermatopathology 2022, via PubMed Central (PMC9397077)

Park and Yun, Dermatopathology 2022, Figure 2 panel A, doi:10.3390/dermatopathology9030035. CC BY 4.0. Cropped from the composite figure by Docutis.

Modification: cropped — Panel A of Figure 2 was cropped from the figure image embedded on page 3 of the article PDF in the PMC open-access package PMC9397077.1 (PDF image object 78, 1599 x 564 pixels), source sha256 39a56cb79357ebd92d77fa05d771ea61baa79971fb57379633d859612dff724c, at pixel box left 18, top 17, right 360, bottom 546 with Pillow, then saved as JPEG quality 90 without metadata. Output sha256 6203f5c6b0880038ec5ded15f4c7163d10d3afaf5467823a5ce8d7fd54738e97. No color change, no annotation, and no other edit.
dermoscopy · CC BY 4.0 · Sanghyun Park and Sook Jung Yun

File: assets/media/cases/case-50-dermoscopy.jpg

Source: Park S, Yun SJ. Dermatopathology 2022, via PubMed Central (PMC9397077)

Park and Yun, Dermatopathology 2022, Figure 2 panel B, doi:10.3390/dermatopathology9030035. CC BY 4.0. Cropped from the composite figure by Docutis.

Modification: cropped — Panel B of Figure 2 was cropped from the figure image embedded on page 3 of the article PDF in the PMC open-access package PMC9397077.1 (PDF image object 78, 1599 x 564 pixels), source sha256 39a56cb79357ebd92d77fa05d771ea61baa79971fb57379633d859612dff724c, at pixel box left 370, top 17, right 869, bottom 546 with Pillow, then saved as JPEG quality 90 without metadata. Output sha256 24d499baa114e204b1e1f911fdb5b15daea09800acaf647d8bed692845b2e3a9. No color change, no annotation, and no other edit.

Observations

A fingernail of an adult with a narrow, even, light-brown band running the full length of the plate. The band edges are sharp. The plate surface and the skin around the nail look normal.
A narrow light-brown band made of thin brown parallel lines of similar colour and thickness, evenly spaced, on a light-brown background. The lines stay parallel along the band and the edges are sharp. The plate surface is intact. The periphery of the field is out of focus.

Observation prompts

Do the lines match in colour, thickness, and spacing?
Is the plate surface intact, and is any pigment visible on the skin around the nail?

Features, certainty, and weight

Clinical morphology, dermoscopic structure, and image context are separate. An image mark does not compete with a diagnostic structure.

Clinical morphology

Broken or missing nail plate — Not visible in this image; Supportive

The plate surface is intact. No break, split, or debris is visible.

Canonical pattern: nail-plate-destruction. Educational role: Diagnostic structure. Case certainty and weight stay on this case.

Dermoscopic structure

Regular thin lines in a narrow band — Clearly visible; Major clue

Thin brown longitudinal lines of similar colour and thickness, evenly spaced and parallel, on a light-brown background.

Canonical pattern: longitudinal-nail-plate-lines. Educational role: Diagnostic structure. Case certainty and weight stay on this case.

Case-specific observation

Pigment on the fold skin around the nail — Not visible in this image; Supportive

No pigment is visible on the proximal fold or the skin at the tip. Absence in one frame is not a clearance.

Canonical pattern: not linked. No fold pigment is visible. An absent fold finding is recorded on the case only; no Hutchinson or periungual pattern is created or linked.

Context and image information

None stored on this case.

Differential

Nail matrix nevus

Why it fits: Regular thin parallel lines of one colour.; Narrow band with sharp edges on an intact plate.

Why not: Not recorded

The figure caption gives matrix histopathology for this band.
Nail-unit melanoma

Why it fits: A pigmented band in an adult.

Why not: Regular lines.; Narrow band.; Intact plate.; No visible fold pigment.

Adult bands are weighed carefully; this frame shows regular architecture.
Melanocytic activation

Why it fits: A light-brown band.

Why not: Distinct brown lines rather than a grey homogeneous background.

Activation usually shows grey background with thin grey lines.
Subungual haemorrhage

Why it fits: Colour in the nail.

Why not: Brown longitudinal lines, not red-black spots or a rounded blot.

Blood does not form a band of regular lines.

Closest mimic

Nail-unit melanoma

Any pigmented nail band in an adult raises the question.

Why not

Nail-unit melanoma — The adult toenail case shows bands of differing width and colour with a split plate. Here the lines are regular and the plate is intact. That supports the source diagnosis; it is not a rule.
Subungual haemorrhage — Blood forms a rounded blot with red-black globules, not a band of regular lines.

Reasoning

The figure caption gives nail matrix histopathology for this adult band. The dermoscopic frame shows a narrow band of regular thin parallel lines of one colour on an intact plate, with no visible fold pigment.

Regular line architecture is clearly visible and is the major clue. The intact plate and the absent fold pigment support it, but absence in one frame is weaker than presence. The figure-caption histopathology is the confirmation.

Diagnostic trap

Treating regular lines as a guarantee, or carrying the irregular-but-benign childhood rule into an adult band.

Mentor note

This is the first adult benign nail band in Docutis. Put it beside the childhood bands with irregular lines and beside the adult toenail with irregular bands and a split plate.

Take-home rule

In an adult, a narrow band of regular lines on an intact plate supports a benign reading in this frame. Age changes how the same line clue is weighed, and the decision stays individual.

Management brief

No management category is stored. The source history is not a Docutis recommendation. This brief is not a protocol and remains review required.

A dark blot under a nail (case-g27-06)

Teaching type: Teaching case
Curriculum level: 3 · mimic
Skills: Color under a nail, Blood colour on acral skin
Recorded diagnosis: Subungual haemorrhage
Disease record: subungual-haemorrhage
Confirmation: clinical_diagnosis — The Figure 1 caption of Bertanha and coauthors (Anais Brasileiros de Dermatologia 2024, doi:10.1016/j.abd.2024.01.005), checked 2026-10-02, labels panels A and B hematoma, describing an oval blackish appearance clinically and a purplish hue with globules and distal streaks on onychoscopy. The review states that progression with nail growth is the key diagnostic evidence for haematoma, but it gives no follow-up, clipping, or histopathology for this nail. Confirmation therefore stays at the caption.
Site: Nail unit of one digit

Provenance

clinical · CC BY 4.0 · Laura Bertanha and coauthors

File: assets/media/cases/case-51-clinical.jpg

Source: Bertanha L, Noriega LF, Di Chiacchio NG, Matter A, Di Chiacchio N. Anais Brasileiros de Dermatologia 2024, via PubMed Central (PMC11551238)

Bertanha and coauthors, Anais Brasileiros de Dermatologia 2024, Figure 1 panel A, doi:10.1016/j.abd.2024.01.005. CC BY 4.0. Cropped from the composite figure by Docutis.

Modification: cropped — Panel A of Figure 1 was cropped from the figure image embedded on page 2 of the article PDF in the PMC open-access package PMC11551238.1 (PDF image object 11, 1505 x 1824 pixels), source sha256 8d6c572eb938da676ceb5b0cb7ab80dbe5ffa88103e6cccc58f737ef7bbbb19a, at pixel box left 2, top 2, right 687, bottom 940 with Pillow, then saved as JPEG quality 90 without metadata. Output sha256 3888ed6a05475bdd9455a67e25a9f2d7a21295c31ffa19d656b70d09ea699fcb. No color change, no annotation, and no other edit.
dermoscopy · CC BY 4.0 · Laura Bertanha and coauthors

File: assets/media/cases/case-51-dermoscopy.jpg

Source: Bertanha L, Noriega LF, Di Chiacchio NG, Matter A, Di Chiacchio N. Anais Brasileiros de Dermatologia 2024, via PubMed Central (PMC11551238)

Bertanha and coauthors, Anais Brasileiros de Dermatologia 2024, Figure 1 panel B, doi:10.1016/j.abd.2024.01.005. CC BY 4.0. Cropped from the composite figure by Docutis.

Modification: cropped — Panel B of Figure 1 was cropped from the figure image embedded on page 2 of the article PDF in the PMC open-access package PMC11551238.1 (PDF image object 11, 1505 x 1824 pixels), source sha256 8d6c572eb938da676ceb5b0cb7ab80dbe5ffa88103e6cccc58f737ef7bbbb19a, at pixel box left 2, top 966, right 687, bottom 1822 with Pillow, then saved as JPEG quality 90 without metadata. Output sha256 d769fd8e8d4b465303ccc1dc1959e79896d60039980b1043aa91f8852670362d. No color change, no annotation, and no other edit.

Observations

A nail with a rounded black-maroon blot in the proximal half of the plate and a thin dark streak running toward the free edge. The distal plate is ridged, and the free edge is broken with yellow-brown debris.
A homogeneous black to dark red area under the plate with rounded red to red-black globules along its border and red streaks at its distal end. Fine yellow-white cracks cross the surface. Fine longitudinal plate striations run through the area. Air bubbles are in the field.

Observation prompts

Is the colour brown, or black to dark red?
Does a pigmented band run from the proximal fold, or is the colour a rounded blot?

Features, certainty, and weight

Clinical morphology, dermoscopic structure, and image context are separate. An image mark does not compete with a diagnostic structure.

Clinical morphology

None stored on this case.

Dermoscopic structure

Homogeneous black to dark red area under the plate — Clearly visible; Major clue

A homogeneous black to dark red area without a band of brown lines. It fits blood in this frame and does not exclude a lesion under it.

Canonical pattern: hemorrhagic-structureless-area. Educational role: Diagnostic structure. Case certainty and weight stay on this case.
Band of longitudinal pigmented lines — Not visible in this image; Supportive

No band of brown pigmented lines runs from the proximal fold. Fine longitudinal striations are plate texture seen through the blood.

Canonical pattern: longitudinal-nail-plate-lines. Educational role: Diagnostic structure. Case certainty and weight stay on this case.

Case-specific observation

Rounded red globules along the border — Clearly visible; Supportive

Rounded red to red-black globules line the border of the dark area, with red streaks at its distal end.

Canonical pattern: not linked. Rounded red border globules are clearly visible on the first nail haemorrhage with dermoscopy. A separate pattern id is deferred until a second independent nail blood example exists.
Broken free edge with debris — Clearly visible; Weak

The distal free edge is broken with yellow-brown debris on the clinical frame only. Its cause is not stated.

Canonical pattern: not linked. A broken free edge with debris is visible only on the clinical frame and its cause is not stated. Nail-plate links are counted from dermoscopic frames, so it stays case-specific.
Thin dark streak toward the free edge — Clearly visible; Weak

A thin dark streak runs from the blot toward the free edge in this single frame. Movement with nail growth cannot be read from one frame.

Canonical pattern: not linked. A thin dark streak toward the free edge is seen in one frame. No migration or growth-out is claimed, so it stays case-specific.

Context and image information

None stored on this case.

Differential

Subungual haemorrhage

Why it fits: Homogeneous black to dark red colour.; Rounded red globules at the border.; No melanin band from the fold.

Why not: No follow-up or clipping is stated for this nail.

The caption names it; growth-out with the nail would confirm it.
Nail-unit melanoma

Why it fits: A dark nail lesion with a damaged free edge.

Why not: Red to red-black colour and globules rather than brown longitudinal lines.

Blood can coexist with a tumour; persistent or recurrent blood needs reassessment.
Onychomycosis with dark pigment

Why it fits: A ridged distal plate with debris.

Why not: The dark area is rounded and red-black with globules, proximal to the debris.

Fungal pigment is usually distal and associated with crumbling; it is read separately from the blot.

Closest mimic

Nail-unit melanoma

A dark nail lesion with a damaged free edge raises the melanoma question.

Why not

Nail-unit melanoma — The adult toenail case shows brown bands of differing width with a split plate. Here the colour is a rounded red-black blot with globules and no brown band. Blood can still coexist with a tumour.
Nail matrix nevus — A nevus band is made of brown longitudinal lines from the matrix to the free edge, not a rounded blot.

Reasoning

The review caption labels this nail a haematoma without stating follow-up, clipping, or histopathology. The onychoscopic frame shows a homogeneous black to dark red area with rounded red globules at its border and no band of brown lines.

The blood colour is clearly visible and is the major clue. The border globules support it. The missing melanin band supports it. The broken free edge is weak and unexplained. The confirmation is a peer-reviewed caption only, which is weaker than documented growth-out or histopathology.

Diagnostic trap

Reassuring from the blood colour without follow-up, or reading one frame as proof that the blot is moving out with the nail.

Mentor note

This is the first nail haemorrhage with onychoscopy in Docutis. Compare its rounded red-black blot with the brown longitudinal bands of the melanocytic nail cases.

Take-home rule

Under a nail, homogeneous black to dark red colour with red border globules suggests blood. Follow it out with the nail, and reassess if it persists, recurs, or sits on a band.

Management brief

No management category is stored. The source history is not a Docutis recommendation. This brief is not a protocol and remains review required.