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Subungual Melanoma Biopsy — SCE Dermatology MCQ

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HardDermatological SurgerySubungual Melanoma BiopsySCE Dermatology

A longitudinal nail band requires biopsy. What is the principal diagnostic advantage of a lateral longitudinal nail-unit biopsy?

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

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Correct answer: BIt samples the full longitudinal nail unit and localises the band origin

The best answer is “It samples the full longitudinal nail unit and localises the band origin”. The lateral longitudinal technique can include matrix, bed, proximal and lateral folds and hyponychium in one oriented specimen, helping locate and assess a longitudinal process; it is selected only when its distribution justifies the potential for scarring. The alternatives “It avoids sampling the nail matrix entirely, after specialist assessment”, “It guarantees absence of permanent nail dystrophy, when the full phenotype supports it”, “It removes every melanoma with definitive margins, within an appropriate UK pathway”, “It is preferable for every narrow central band, after clinicopathological correlation” are clinically adjacent possibilities, but they do not fit the defining morphology, distribution, histopathology, risk signal or management sequence in this stem.

Reference: NICE NG14 melanoma recommendations: https://www.nice.org.uk/guidance/ng14/chapter/Recommendations