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Two-Component Pattern — SCE Dermatology MCQ

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HardSkin CancerTwo-Component PatternSCE Dermatology

A changing 9 mm pigmented lesion has asymmetry, an irregular network, eccentric blue-white structures and an atypical vascular focus on dermoscopy. There is no palpable nodal disease. What diagnostic procedure should be arranged?

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

Reveal the answer and explanation

Correct answer: D — Complete excision biopsy of the lesion with a 2 mm clinical margin

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

B is correct. A lesion suspicious for melanoma should normally undergo complete excision biopsy, including the whole lesion and approximately 2 mm of clinically normal skin, with sufficient depth for accurate histological assessment. This preserves architecture and permits measurement of Breslow thickness, which determines the subsequent wide-excision margin and staging pathway. Partial shave or punch sampling may miss the most advanced component and compromise depth assessment. A definitive 3 cm margin before histology is excessive and bypasses staging. The original terminology-based item used a debatable label for a mixed pattern; this version tests the consequential action when multiple melanoma-specific structures coexist.

Reference: NICE HTG388 melanoma diagnostic practice: https://www.nice.org.uk/guidance/htg388/chapter/3-Clinical-need-and-practice