Large aneurysmal dermatofibroma mimicking melanoma in an adolescent: A case report
Bibliographic record
Abstract
Hemosiderotic dermatofibroma (HDF) is an infrequent variant of dermatofibroma, made up of small blood vessels, hemosiderin deposits, and extravasated erythrocytes. HDF closely resembles melanoma, with irregular borders and colour changes on clinical examination and atypical cell organization on dermoscopy and can pose a diagnostic dilemma. We report the case of a large (5cm) subcutaneous hemosiderotic/aneurysmal DF (H/ADF) that appeared on the flank of 17-year-old, otherwise healthy, male patient. The mass evolved over two years, with purple discoloration noticed three months prior. Clinical examination revealed a palpable moveable mass overlying the left hip in the subcutaneous tissues measuring approximately 4 x 4 cm. Because of both the substantial size of the mass and diagnostic uncertainty, the decision was made to proceed with surgical resection. The lesion was resected without complication, although there was copious bleeding initially. Pathological findings showed a dermatofibroma, cellular subtype, with aneurysmal change. Sections showed a solid, cellular proliferation composed of plump ovoid to spindle cells arranged in a storiform pattern and short fascicles punctuated by areas of hemorrhage and associated hemosiderin pigment deposition. Occasional multinucleated giant cells were seen. At 1 month follow-up, the patient was in good condition, and completely asymptomatic. There was no recurrence. Pediatric surgeons should be aware that rare dermatofibroma variants, such as aneurysmal dermatofibroma, can clinically resemble melanoma and should be treated with excisional biopsy. Diagnosis should always be confirmed with histopathology and immunohistochemistry.
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How this classification was reachedexpand
Full frame machine prediction
Teacher imitationNot calibrated prevalence, not ground truth. Human validation pending. The Gemma side is a direct model label for every work in the frame, read from the title-only record. The Codex side is a classifier learned from the 10,348 direct Codex labels and calibrated to design-weighted sample rates; fields without enough sample support carry no Codex call. Candidate is the union of the two sides; consensus is their intersection. These outputs are machine_predicted_unvalidated and are not human labels.
Distilled classifier scores by category (both heads)
| Category | Codex | Gemma |
|---|---|---|
| Metaresearch | 0.000 | 0.002 |
| Meta-epidemiology (narrow) | 0.002 | 0.001 |
| Meta-epidemiology (broad) | 0.001 | 0.001 |
| Bibliometrics | 0.002 | 0.001 |
| Science and technology studies | 0.002 | 0.001 |
| Scholarly communication | 0.001 | 0.002 |
| Open science | 0.001 | 0.001 |
| Research integrity | 0.003 | 0.002 |
| Insufficient payload (model declined to judge) | 0.002 | 0.001 |
Machine scores (provisional)
The two teacher heads of the student model, read on this work. A score orders the frame for review; it never asserts a category, and the validation status ships verbatim with every row.
Baseline scores from an immature model (maturity gate not passed, 7 training rounds). Scores rank; they never assert a category.
score_only:v0-immature-baseline · verbatim from the scoring run: score_only means the number may rank works, and no category label ships from itClassification
machine, unvalidatedMachine predicted; a candidate call from one source (direct Gemma or distilled Codex), not a consensus.
How this classification was reached, model by model and score by score, is at the end of the page under "How this classification was reached".