Mesalamine-induced hypersensitivity pneumonitis

A 23-year-old woman was admitted with a history of 2 weeks of cough, fever and bilateral lung infiltrates. She had been diagnosed 2 months before as having ulcerative proctitis and was treated with mesalamine, which induced a full remission, but 3 antibiotic regimens failed to improve her lung disease. Since computerized tomography revealed bilateral peripheral lung infiltrates and her eosinophile count was elevated, the diagnosis of drug- induced eosinophilic pneumonia was suggested. Mesalamine and antibiotics were stopped and oral corticosteroids begun. She became almost asymptomatic a week after mesalamine withdrawal, and the x-ray became normal.