A 45-year-old agricultural worker from rural Tamil Nadu has slowly enlarging verrucous plaques over the dorsum of the foot for several years. Biopsy of the lesion shows large, round, thick-walled, brown-coloured cells dividing by transverse and vertical septa within giant cells. These structures are diagnostic of which condition?

• A Eumycetoma due to Madurella mycetomatis
• B Phaeohyphomycosis with pigmented hyphae
• C Chromoblastomycosis with muriform cells ✓
• D Lobomycosis with chain-forming yeast cells

Explanation

Chromoblastomycosis follows traumatic inoculation by dematiaceous fungi such as Fonsecaea pedrosoi and produces warty, cauliflower-like plaques on exposed lower limbs. The diagnostic hallmark is the muriform cell, also called the medlar body or copper penny body: a brown, thick-walled cell that divides by planar septation in both planes. Eumycetoma would show grains and draining sinuses rather than verrucous plaques, phaeohyphomycosis shows pigmented hyphal elements without muriform cells, and lobomycosis shows chains of yeast-like cells linked by isthmuses.

Reference: Harrison's Principles of Internal Medicine, 21st ed.

High-yield for: NEET PGINI-CETNExTFMGEUSMLEPLABMRCP

Written and medically reviewed by the StethoPrep medical team.