Diffuse pulmonary diseases seen in patients receiving chemotherapy have a wide variety of etiologies including infection, involvement with the underlying disease, injury from radiation or diagnostic agents, and toxicity from chemotherapeutic drugs. In addition to concomitantly used therapeutic agents, previously administered cytotoxic drugs may enhance the toxicity of radiotherapy and vice versa. Together with the clinician, the radiologist may be able to assess the probability of drug-induced lung disease by correlating radiographic and clinical data. Useful clinical data include signs and symptoms related to the lungs, pulmonary function test results, dose and schedule of drug administration, and information concerning concomitant or previous drug or radiation therapy. Useful radiographic data include the distribution of densities seen on the chest radiograph, the presence or absence of thoracic adenopathy, and the presence or absence of pleural effusion. The diagnosis is difficult, and thus the incidence of clinical and subclinical drug-induced pneumonitis is not accurately known.
