Lichen Planus — RACP Adult Medicine MCQ

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EasyDermatologyLichen PlanusRACP Adult Medicine

A 32-year-old woman presents with a 6-month history of widespread pruritic, violaceous, polygonal, flat-topped papules on her wrists and ankles. She also has a lacy white pattern on her buccal mucosa. What is the most likely diagnosis?

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Correct answer: E — Lichen planus

The 6 Ps of lichen planus: pruritic, purple (violaceous), polygonal, planar (flat-topped) papules and plaques. Wickham striae (the lacy white pattern on buccal mucosa) are pathognomonic. Wrists and ankles are classic distribution sites. Histology shows a band-like lymphocytic infiltrate at the dermo-epidermal junction with civatte bodies (apoptotic keratinocytes). First-line treatment is potent topical corticosteroids.

Reference: eTG – 2025 – Dermatology