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Seborrhoeic keratosis — SCE Dermatology MCQ

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HardDermoscopySeborrhoeic keratosisSCE Dermatology

A longstanding seborrhoeic-keratosis-like trunk lesion develops a new eccentric blue-black structureless focus and irregular vessels. Milia-like cysts remain elsewhere in the lesion. What is the safest next step?

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Correct answer: A — Arrange excision for histology because melanoma cannot be excluded within the changing lesion

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

C is correct. Seborrhoeic keratoses can be pigmented and melanomas can display keratin-like structures or collide with a benign lesion. A new eccentric blue-black area and irregular vessels break the reassuring global pattern, so diagnostic histology is required. Milia-like cysts are supportive but not absolute proof of benignity. Destructive curettage or cryotherapy without histology may remove the diagnostic tissue, and previous stability does not neutralise a documented new change. Complete excision is preferable when melanoma is suspected because architecture and depth must be assessed. This replacement removes the contradictory original stem, which described a completely stable classic lesion yet asked which malignancy must always be excluded.

Reference: PCDS seborrhoeic keratosis guidance: https://www.pcds.org.uk/clinical-guidance/seborrhoeic-keratosis-syn-seborrhoeic-wart-basal-cell-papilloma