Mushroom worker's lung.

Two cases of an acute chest illness occurring in mushroom workers are described. In one patient, who was severely ill, a lung biopsy was obtained which showed a pattern of alveolitis and interstitial fibrosis. The serum of both patients gave a precipitin reaction to an extraction of mushroom compost after spawning, but no reaction occurred to a variety of hay antigens used in the diagnosis of farmer's lung. A provocation test undertaken in one patient demonstrated a reaction to the inhalation of a dilute extract of mushroom compost after spawning. The most severely ill patient made a full clinical and functional recovery without steroid therapy.