Cytologic and histologic findings of iron pill-induced injury of the lower respiratory tract.

In the airways, iron pill-induced mucosal injury is uncommon and can lead to necrosis and stricture of the respiratory tracts. The process is characterized by mucosal ulceration with deposition of crystalline iron particles, and the diagnosis is usually made on tissue biopsies. We report a case of iron-sulfate-induced mucosal injury in the bronchial washing and biopsy of a patient receiving therapeutic oral iron supplementation with no known aspiration event. Clinically, the patient presented with hemoptysis, and bronchoscopy detected ulcerated main stem bronchus mucosa clinically suspicious for a neoplastic process. Bronchial washings revealed reactive epithelial cells and numerous histiocytes with both intracellular and extracellular refractile brown crystalline material, which was positive on iron stain. The histologic findings on biopsy showed mucosal ulceration with deposits of extracellular crystalline iron particles. These histologic changes are similar to those seen in iron pill-induced mucosal injury of the upper gastrointestinal tract in patients with "iron pill" gastritis. The cytologic and histologic features of iron pill-induced airway injury clinically can mimic cancer. The presence of extracellular and intracellular crystalline iron in the airway lumen and/or mucosa with associated varying degrees of ulceration and inflammation confirms the diagnosis.