Airway Injury Caused by Aspiration of Iron Sulfate Pills: A Series of 11 Cases

It is not widely recognized that iron (ferrous sulfate) pill aspiration causes airway damage. Clinical diagnosis is challenging because patients are often unaware that they have aspirated a pill. The literature on this entity consists mainly of case reports. The aim of this study is to describe the clinical and pathologic features of iron pill aspiration in a series of 11 patients. A retrospective review of our pathology archives was performed to identify cases of iron pill aspiration (2013-2023). All available histologic and cytologic material was rereviewed. Clinical information was collected from the electronic medical record, and imaging studies were rereviewed. Eighteen endobronchial biopsies were identified from 11 patients (7 women and 4 men; mean age, 70 years; range, 44-82 years). Eight patients had corresponding cytology (20 specimens). Medication history was available in 9 of 11 patients, all of whom were taking iron sulfate pills. Two patients reported possible aspiration episodes; 4 had risk factors for aspiration. The diagnosis of iron pill aspiration was suspected prior to biopsy in only 1 case. Histologically, iron pill particles were yellow, golden brown, or gray, were elongated and crystal or fiber like, and stained strongly with an iron stain. Common histologic findings included mucosal ulceration, acute and/or chronic inflammation, fibrosis, and squamous metaplasia. Iron pill particles were also identified in 11 cytology specimens from 6 patients. On Papanicolaou staining, iron pill particles were yellow to golden, fiber like, refractile, and crystalline. Reactive epithelial cells, squamous metaplasia, and acute inflammation were common. The combination of iron pill intake and discolored mucosa on bronchoscopy is a potential clue to the diagnosis of iron pill aspiration. Pathologists should familiarize themselves with the appearance of iron pill particles in endobronchial biopsies and cytology specimens from the respiratory tract as this diagnosis is seldom suspected on clinical grounds, and most patients lack a history of aspiration.