Farmer's lung: Clinical, pathologic and immunologic study of twenty-four patients

Abstract

Clinical, pathologic, roentgenologic and immunologic findings in twenty-four cases of farmer's lung are presented. The findings are correlated with the three stages of the disease. Pathologically, farmer's lung is generally considered an interstitial pneumonitis with granuloma formation. Our study indicates a much greater variety of histopathologic changes than previously described. This includes interstitial pneumonitis without granuloma formation, organizing endobronchial exudate and the finding of foreign material in many biopsy specimens. This foreign body material may be of etiologic importance. Circulating antibodies can be demonstrated by the agar gel diffusion technic in patients with recent and active disease. This procedure may afford a simple diagnostic test for the confirmation of farmer's lung. The disease is reversible in the early stages. Progressive pulmonary fibrosis and emphysema can develop with repeated exposure and was the cause of death in four of the twenty-four patients. The only known cure is removal of the patient from his environment.