[Pulmonary disease caused by Mycobacterium avium presenting as a solitary cavity with a thickened wall]

A 46-year-old man was admitted for evaluation of a solitary pulmonary cavity in the apey of the left lung. Because two transbronchial biopsies followed by brushing and washing and sputum cytology did not yield any diagnostic findings, the patient was treated with INH, RFP and SM under a tentative diagnosis of pulmonary tuberculosis. The shadow decreased over two months with combination therapy, but increased again after the dose of SM was decreased. We performed a left upper lobectomy to diagnose either multi-drug-resistant pulmonary tuberculosis or lung cancer. Pathological examination of the resected lung revealed epitheloid cell granulomas with areas of caseous necrosis. Smooth chromophoric colonies were isolated on an Ogawa egg medium, and were identified as M. avium by PCR and DDH. A diagnosis of pulmonary M. avium was made. A chest X-ray film taken two years later was normal. Pulmonary M. avium disease developed in this patient, who had no predisposing lung pathologies.