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Naevus Sebaceus — SCE Dermatology MCQ

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ModerateSkin CancerNaevus SebaceusSCE Dermatology

A 30-year-old man presents with a longstanding yellowish plaque on his scalp present since birth. It was initially a smooth hairless area but has recently developed warty papules within it. What was the original lesion and what is the concern?

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Correct answer: E — Naevus sebaceus of Jadassohn — risk of secondary neoplasms (BCC, trichoblastoma)

Naevus sebaceus of Jadassohn is a congenital hamartoma of sebaceous glands typically presenting as a smooth, hairless, yellowish plaque on the scalp or face. At puberty, it becomes verrucous/thickened due to hormonal stimulation of the sebaceous glands. The lifetime risk of secondary neoplasia within the naevus is approximately 10-30%, most commonly trichoblastoma (benign) rather than BCC (which was previously overestimated). The development of new papules or nodules within a naevus sebaceus should prompt excision and histological examination. Prophylactic excision in adolescence/early adulthood is commonly recommended.

Reference: BAD 2019; Paediatric Dermatology Textbook