A 25-year-old male presents with a painless, slowly progressive verrucous plaque on the dorsum of the right foot for 3 years following a thorn prick. Biopsy shows pseudoepitheliomatous hyperplasia with 'Medlar bodies' (muriform cells — round, brown, thick-walled cells with internal septa). Which organism most commonly causes this infection in India?

• A Sporothrix schenckii — causes sporotrichosis with lymphocutaneous spread
• B Madurella mycetomatis — causes black-grain eumycetoma, not chromoblastomycosis
• C Cladophialophora carrionii — causes chromoblastomycosis in arid regions (Caribbean, Venezuela), less common in India
• D Fonsecaea pedrosoi — the most common cause of chromoblastomycosis (chromomycosis) worldwide and in India ✓

Explanation

Chromoblastomycosis (chromomycosis) is a chronic subcutaneous fungal infection caused by dematiaceous (melanised, black) fungi, most commonly Fonsecaea pedrosoi globally and in India. The pathognomonic finding on biopsy is 'medlar bodies' (sclerotic bodies / muriform cells) — round, brown, thick-walled cells with vertical and horizontal septa resembling 'copper pennies.' Infection follows traumatic inoculation with contaminated soil/wood. Sporothrix causes lymphocutaneous sporotrichosis with cigar-shaped yeast on culture/biopsy. Madurella causes eumycetoma (grains in discharging sinus tracts, not muriform cells).

Reference: Ananthanarayan & Paniker's Textbook of Microbiology, 11th ed.

High-yield for: NEET PGINI-CETNExTFMGEUSMLEPLABMRCP

Written and medically reviewed by the StethoPrep medical team.