A 40-year-old agricultural worker from rural Brazil presents with chronic cough and painful ulcerated lesions on the oral mucosa. Biopsy of a pulmonary lesion reveals large round yeast cells, 15 to 30 micrometres wide, with multiple buds attached around the periphery by narrow necks. This microscopic appearance is characteristic of which fungus?

• A Paracoccidioides brasiliensis ✓
• B Blastomyces dermatitidis
• C Histoplasma capsulatum
• D Sporothrix schenckii

Explanation

Multiple peripheral buds arranged like a ship steering wheel or pilot wheel is the classic description of Paracoccidioides brasiliensis, a dimorphic fungus endemic to Latin America that commonly involves lungs and mucous membranes of the mouth. Blastomyces shows broad-based single buds, Histoplasma shows small intracellular yeasts within macrophages and Sporothrix shows cigar-shaped yeasts, so the pattern of multiple simultaneous buds distinguishes paracoccidioidomycosis from every other systemic dimorphic infection.

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

High-yield for: NEET PGINI-CETNExTFMGEUSMLEPLABMRCP

Written and medically reviewed by the StethoPrep medical team.