[Farmer's lung complicated by bilateral pneumothorax and mediastinal emphysema].

A 35-year-old woman was admitted to the hospital because of severe coughing and right-sided chest pain. She had worked on a farm for 13 years. For the preceding 2 years, she noticed a productive cough, a mild fever, and dyspnea after working in a barn for longer than 6 hours. Chest radiological examinations revealed low lung volumes, especially in the right upper lobe, and diffuse small granular shadows in both lung fields. Pathological examinations of lung specimens, which were obtained by transbronchial lung biopsy, showed alveolitis and granulomas in the interstitium. Micropolyspora faeni organisms were detected in hay from the barn. A M. faeni serum precipitation test revealed that her serum had antibodies against that organism. From these findings, we gave her a diagnosis of chronic farmer's lung. Prednisolone was given because her dyspnea and hypoxemia had increased. During the steroid treatment, bilateral pneumothorax and mediastinal emphysema developed. Bullae were removed surgically because she did not respond well to medical treatment. Although steroid administration may have caused these complications, bilateral pneumothorax and mediastinal emphysema are rare in patients with chronic farmer's lung.