Answer: Rhinoscleroma

Histology: The submucosa is filled with a nodular infiltrate of clear cells with interspersed plasma cells and lymphocytes. The lesional cells have centrally placed small and compact nuclei, and abundant clear cytoplasm with subtle granularity. The clear cells are strongly CD68 positive and cytokeratin negative. A Warthin-Starry stain demonstrates abundant gram-negative bacteria within the cytoplasm of the clear cells.

Discussion: Rhinoscleroma is a chronic granulomatous infectious disease primarily occurring in the nasal cavity and nasopharynx, and caused by Klebsiella rhinoscleromatis – a gram-negative bacteria. It generally occurs during the first three decades of life, is a disease of the lower socioeconomic class, is uncommon in the United States but common in certain endemic regions of the world such as Egypt and parts of Central and South America. The disease progresses along three clinical stages: A rhinitic stage characterized by mucopurulent nasal discharge. A florid stage characterized by mucosal thickening, often result in nasal obstruction. And a fibrotic stage characterized by lesional resolution.

The hallmark histologic finding is the so called Mikulicz cell – a macrophage with abundant clear to foamy cytoplasm. These are admixed with other inflammatory cells including plasma cells, lymphocytes and neutrophils. These cells are most abundant during the florid stage, and diminish in number during the fibrotic stage. Demonstration of the intracellular organisms using a Warthin-Starry stain is the easiest way to confirm the diagnosis. The Klebsiella organisms appear as stubby gram negative rods within the cytoplasm of the macrophages.

The use of antibiotics (e.g. tetracycline) is very effective in clearing the infection. Surgical intervention is sometimes necessary to open a narrowed airway.