Hypersensitivity pneumonitis and extrinsic asthma. An unusual association.

A farmer who had no prior history of pulmonary disease developed tightness in the chest of rapid onset, shortness of breath, fever, and pulmonary infiltration while farming. The symptoms of his disease worsened with repeated exposure to the dusty farm field but remitted after each of five hospitalizations. Provocative challenge with inhalation of a water-soluble extract of dust from the field reproduced both asthmatic and pneumonitic features of the disease, while administration of corticosteroids clinically controlled the entire process. The data suggest a common cause for asthma and pneumonitis in this patient.