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Dermatofibroma — SCE Dermatology MCQ

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HardSkin CancerDermatofibromaSCE Dermatology

A presumed dermatofibroma on the thigh has enlarged from 7 mm to 18 mm over nine months and is now nodular and focally ulcerated. Dermoscopy no longer shows a symmetric central white patch. What is the best next step?

Educational content. Not a substitute for clinical judgement or local policy.

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Correct answer: D — Arrange complete histological assessment to exclude DFSP or another malignant mimic

Explanation lettering: D = shown as A · C = shown as B · A = shown as C · B = shown as D

B is correct. A small stable dermatofibroma with typical morphology can be diagnosed clinically, but rapid enlargement, size, nodularity, ulceration or loss of symmetry should trigger histological assessment. DFSP, cellular dermatofibroma, melanoma and other spindle-cell tumours can mimic a dermatofibroma, and the dimple sign is not absolute proof of benignity. Cryotherapy and corticosteroid do not resolve diagnostic uncertainty and may compromise subsequent assessment. Excision depth and margins are then guided by histology rather than assumed from the initial label.

Reference: Primary Care Dermatology Society: dermatofibroma: https://www.pcds.org.uk/clinical-guidance/dermatofibroma-syn-histiocytoma