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Giant Congenital Melanocytic Naevus — SCE Dermatology MCQ

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HardPaediatric DermatologyGiant Congenital Melanocytic NaevusSCE Dermatology

A 28-year-old man has a large congenital melanocytic naevus (CMN) on his trunk measuring 25 cm at birth. What is the estimated lifetime melanoma risk for giant CMN (>20 cm projected adult size)?

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

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Correct answer: C — A several-percent lifetime melanoma risk requiring specialist surveillance

The best answer is “A several-percent lifetime melanoma risk requiring specialist surveillance”. NICE bases melanoma diagnosis, excision margins and nodal assessment on complete histology, Breslow thickness, ulceration and clinical stage, with specialist review of suspicious or changing lesions. The alternatives “100%, when the full phenotype supports it”, “50%, within an appropriate UK pathway”, “Less than 1%, after clinicopathological correlation”, “2-5%, after specialist assessment, when the full phenotype supports it” 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