Mycosis Fungoides — RACP Adult Medicine MCQ

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ModerateDermatologyMycosis FungoidesRACP Adult Medicine

A 55-year-old woman presents with widespread violaceous plaques and papules on her trunk, with an annular configuration. Skin biopsy shows a band-like lymphocytic infiltrate with epidermotropism and Pautrier microabscesses. What is the most likely diagnosis?

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Correct answer: A — Mycosis fungoides

Mycosis fungoides is the most common cutaneous T-cell lymphoma. Early patch/plaque stage shows epidermotropism of atypical lymphocytes with Pautrier microabscesses (collections of atypical T cells within the epidermis). It typically presents with persistent patches and plaques in non-sun-exposed areas (bathing trunk distribution). Treatment of early-stage disease includes skin-directed therapies (topical corticosteroids, phototherapy, nitrogen mustard). Advanced disease requires systemic therapy.

Reference: eTG – 2025 – Dermatology; NCCN – 2025 – CTCL Guidelines