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Chromoblastomycosis histopathology — DTM&H MCQ

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HardDermatological Tropical ConditionsChromoblastomycosis histopathologyDTM&H

A slowly progressive tropical verrucous plaque yields thick-walled brown muriform bodies on potassium-hydroxide microscopy. Which pathogen category is responsible?

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Correct answer: C — Traumatically inoculated dematiaceous fungi such as Fonsecaea species

The best answer is “Traumatically inoculated dematiaceous fungi such as Fonsecaea species”. Pigmented muriform or sclerotic bodies are the defining tissue form of chromoblastomycosis caused by dematiaceous fungi after traumatic implantation. Histoplasma appears as small intracellular yeasts rather than brown muriform bodies; M. ulcerans produces necrotising ulcers; Leishmania produces intracellular amastigotes; and Onchocerca produces worms and microfilariae. The microscopic discriminator is stronger than lesion morphology alone.

Reference: WHO, Chromoblastomycosis fact sheet: https://www.who.int/news-room/fact-sheets/detail/chromoblastomycosis