[Hypersensitivity pneumonitis-like disease caused by exposure to Mycobacterium avium complex in bathtub water at home: a case report].

We report here a case of hypersensitivity pneumonitis-like disease in an adult, likely due to exposure to Mycobacterium avium complex (MAC) in his bathtub water at home. A 63-year-old man was referred to our hospital with exertional dyspnea. Chest computed tomography showed bilateral, diffuse, centrilobular ground-glass nodules. Bronchoalveolar lavage showed marked lymphocytosis. Transbronchial biopsy showed epithelioid cell granulomas and lymphocyte alveolitis. Cultures of the patient's sputum and bathtub water yielded MAC. Variable-number tandem repeat analysis of the MAC strains in the sputum and bathtub water samples showed that the strains were genetically identical. The clinical condition of the patient improved at home under chemotherapy by avoiding the use of the bathtub.