A case of Mycobacterium avium pulmonary disease accompanied with pleural effusion

Nontuberculous mycobacterial infection is seldom complicated with pleural involvement. We report a very rare case of M. avium pulmonary disease accompanied with pleural effusion. A 76-year-old man was admitted to our hospital because of cough and low-grade fever. A chest radiograph and computed tomograph showed centrilobular nodules in the right middle lobe and left lingula, and right pleural effusion. The patient had had a right spontaneous pneumothorax 50 days before his admission. The sputum smear was negative for acid fast bacilli. The smear of pleural effusion was positive for acid fast bacilli, the level of adenosine deaminase in the effusion was markedly elevated, and pleural effusion was positive for M. avium as assessed by polymerase chain reaction (PCR). The pleural biopsy specimen showed fibrous change without granuloma, while the transbronchial biopsy specimen showed noncaseous epithelioid granulomas. We considered that the pneumothorax was caused by the spread of pulmonary M. avium infection to the visceral pleura with its perforation.