[Diffuse infiltrative lung diseases due to allergy and iatrogenic causes]

Iatrogenic and hypersensitivity infiltrative pneumonias comprise 3 distinct entities: extrinsic allergic alveolitis, drug-induced pneumonia and radiation-induced pneumonia. The diagnosis of the latter is usually easy, except for the recently identified postradiation bronchiolitis obliterans organizing pneumonia. Diagnosis of extrinsic allergic alveolitis is based on the association of clinical, radiological, functional, immunological criteria and bronchoalveolar lavage fluid analysis. The polymorphous presentation of drug-induced pneumonia makes its diagnosis critical except for a few causes such as amiodarone pneumonia or lipoid pneumonia.