An adolescent boy who swims in village ponds presents with a friable, easily bleeding polypoidal mass in the nasal cavity. Biopsy shows large thick-walled sporangia filled with numerous endospores. The causative agent is:

• A Blastomyces dermatitidis
• B Rhinoscleroma caused by Klebsiella pneumoniae subspecies rhinoscleromatis
• C Rhinosporidium seeberi ✓
• D Conidiobolus coronatus

Explanation

Rhinosporidiosis, endemic in southern India and Sri Lanka and linked to stagnant freshwater, produces vascular nasal polyps whose biopsy shows sporangia up to several hundred micrometers containing endospores. Klebsiella causes sclerotic plaques with Mikulicz cells, Conidiobolus causes facial subcutaneous swelling, and Blastomyces shows broad-based budding yeasts, none of which form sporangia.

Reference: Rook's Textbook of Dermatology, 9th ed.

High-yield for: NEET PGINI-CETNExTFMGEUSMLEPLABMRCP

Written and medically reviewed by the StethoPrep medical team.