Radiologic findings in farmer's lung. Prognosis and correlation to lung function.

We classified the radiologic findings of 93 patients with acute or subacute farmer's lung (FL) disease by type and severity of the change in chest x-ray film. Acute radiologic changes, further divided as nodular, ground-glass, or striated patchy opacities, were found in 78/93 patients at the first evaluation; 11 showed chronic changes (radiologic "fibrosis"), which persisted unchanged throughout the follow-up period; and four initially had a normal chest x-ray film. Patients were followed up 23 months on an average. The more severe the radiologic change at the first evaluation, the more impaired the diffusing capacity (Dsb). Severe radiologic changes disappeared more slowly than the less severe ones. The differences in the initial pulmonary function values between the two groups disappeared during the follow-up. The type of acute change did not predict the recovery of respiratory performance. Treatment with oral corticosteroids did not affect the outcome of lung function or appearance of chronic changes, although corticosteroids seemed to hasten the disappearance of diffuse opacities. At the final evaluation, the chest x-ray film was normal in 55/93 patients. Chronic changes were detected in 38 patients. Severe radiologic appearance and striated patchy opacities predisposed to development of chronic changes.