A 30-year-old man from Kerala who swims regularly in ponds presents with a painless, pinkish, lobulated polypoidal mass in his nose that bleeds on touch. Biopsy shows large thick-walled sporangia filled with numerous endospores. What is the causative agent?

• A Cryptococcus neoformans
• B Rhinosporidium seeberi ✓
• C Conidiobolus coronatus
• D Blastomyces dermatitidis

Explanation

Rhinosporidiosis presents as a vascular, polypoidal nasal mass in persons exposed to stagnant fresh water, classically in southern India and Sri Lanka. Histology shows large sporangia containing endospores. Although long called a fungus, molecular studies place Rhinosporidium seeberi among aquatic protists (Mesomycetozoea), but Indian exam convention still lists it under fungi. Conidiobolus causes chronic rhinoentomophthoromycosis with nasal swelling rather than a friable polyp, Cryptococcus forms encapsulated yeasts, and Blastomyces forms broad-based budding yeast cells.

Reference: Paniker's Textbook of Medical Parasitology and Mycology, 8th ed.

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Written and medically reviewed by the StethoPrep medical team.