Biopsy of a nodular granulomatous nasal mass in a young woman shows foamy histiocytes containing gram-negative bacilli (Mikulicz cells). Which organism is responsible?

• A Klebsiella pneumoniae subspecies rhinoscleromatis ✓
• B Klebsiella pneumoniae subspecies ozaenae
• C Mycobacterium leprae
• D Rhinosporidium seeberi

Explanation

Rhinoscleroma is a chronic granulomatous disease of the nose and upper airway caused by Klebsiella pneumoniae subspecies rhinoscleromatis. Its hallmark is the Mikulicz cell, a large foamy macrophage packed with bacilli demonstrable by Warthin-Starry or Giemsa stain. Subspecies ozaenae causes atrophic rhinitis (ozena) with foul-smelling crusts but does not produce granulomatous nodules with Mikulicz cells. Leprosy involves skin nerves, and Rhinosporidium is a fungus-like organism producing vascular polyps with sporangia.

Reference: Robbins and Cotran Pathologic Basis of Disease, 10th ed.

High-yield for: NEET PGINI-CETNExTFMGEUSMLEPLABMRCP

Written and medically reviewed by the StethoPrep medical team.