Rhinoscleroma is a chronic granulomatous disease of the upper respiratory tract caused by a gram-negative organism, Klebsiella rhinoscleromatis.  It is uncommon in the US, but is endemic in parts of Central and South America,  Egypt, Africa, and Eastern Europe.  Mucopurulent discharge characterizes the rhinitic stage, followed by mucosal thickening during florid stage (seen here).  The disease resolves with marked fibrosis.

This is a sinonasal rhinoscleroma during florid stage with marked cellular infiltrates consisting of lymphocytes and plasma cells.  There are many macrophages with clear to foamy cytoplasm (Mikulicz cells) that harbor Klebsiella rhinoscleromatis (see Warthin-Starry stain).

Higher magnification view of the previous slide depicting the Mikulicz cells.

Rhinoscleroma is rare in the US, but occurs in regions of poor living conditions that foster the spread of the bacteria. Three clinical stages define the disease: 1) rhinitic 2) florid, and 3) fibrotic. Symptoms vary with the location of the infection. Nasal cavity (septum) is the most common site, but other sites of infection include: paranasal sinuses, orbit, larynx, tracheobronchial tree, and middle ear. Tetracycline is the treatment of choice with excellent prognosis. However, significant airway obstruction requires surgical excision.