Drug-induced lung disease: a pragmatic classification incorporating HRCT appearances.

Drug-induced lung disease frequently poses a diagnostic challenge. Knowledge of common radiological patterns of lung involvement and corresponding histopathologic diagnoses can facilitate management of individual patients. We outline a framework for understanding radiological and histologic patterns of drug-induced lung disease. Diffuse forms of drug-induced lung disease include processes that mimic acute respiratory distress syndrome (ARDS) and diffuse alveolar hemorrhage. These patterns of drug-induced lung disease are especially common in patients receiving cytotoxic chemotherapeutic agents. Chronic forms of drug-induced lung disease include many of the interstitial pneumonias seen more commonly in patients with idiopathic disease. Bronchiolitis obliterans organizing pneumonia and eosinophilic pneumonia are nonspecific patterns of drug-induced lung disease that are radiologically and histologically indistinguishable from their idiopathic counterparts. In some patients organizing pneumonia and eosinophilic pneumonia mimic the radiological appearance of neoplastic disease.