Chromoblastomycosis Histology — SCE Infectious Diseases MCQ

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HardTropical & Imported InfectionsChromoblastomycosis HistologySCE Infectious Diseases

A 35-year-old man with HIV (CD4 450, VL <50 on ART) presents with a chronic plaque on his nose that has been slowly enlarging over 6 months. He is from Ethiopia and reports previous skin trauma at that site. Biopsy shows pseudoepitheliomatous hyperplasia with large spherical cells (thick-walled, with internal septations — 'pilot wheel' or 'copper penny' appearance). What is the diagnosis?

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Correct answer: B — Chromoblastomycosis — thick-walled sclerotic (Medlar) bodies with internal septations are pathognomonic

Sclerotic bodies (also known as Medlar bodies, muriform cells, or 'copper pennies') — thick-walled brown pigmented spherical cells with internal cross-septations — are pathognomonic of chromoblastomycosis on histology. This chronic subcutaneous mycosis is caused by dematiaceous fungi (Fonsecaea, Cladophialophora, Phialophora) after traumatic inoculation. It presents as slowly progressive warty/verrucous plaques, typically on exposed extremities. Treatment: Itraconazole 200–400 mg daily ± Terbinafine 250–500 mg daily for prolonged courses (months to years). Surgical excision for small lesions.

Reference: WHO 2024 – Chromoblastomycosis; ISHAM 2017