Interstitial lung disease induced by drugs and radiation.

An ever-increasing number of drugs can reproduce variegated patterns of naturally occurring interstitial lung disease (ILD), including most forms of interstitial pneumonias, alveolar involvement and, rarely, vasculitis. Drugs in one therapeutic class may collectively produce the same pattern of involvement. A few drugs can produce more than one pattern of ILD. The diagnosis of drug-induced ILD (DI-ILD) essentially rests on the temporal association between exposure to the drug and the development of pulmonary infiltrates. The histopathological features of DI-ILD are generally consistent, rather than suggestive or specific to the drug etiology. Thus, the diagnosis of DI-ILD is mainly made by the meticulous exclusion of all other possible causes. Drug dechallenge produces measurable improvement in symptoms and imaging in the majority of patients, whereas corticosteroid therapy is indicated if symptoms are present or drug dechallenge is without an effect. Rechallenge is justified in a minority of patients, and is discouraged for diagnostic purposes only. Pneumotox (www.pneumotox.com) provides updated information on drug-induced respiratory disease.