Infectious bulla of the lung caused by Mycobacterium intracellulare

A healthy 24-year-old man who was admitted to our hospital was suspected of having an infectious bulla of the lung because an intrabullous effusion was seen on a chest radiograph. A bulla of the right lung had been found 2 years earlier during a periodic health examination. On a chest radiograph, a bullous lesion with a niveau-like shadow (14 × 7 cm) was noted in the right lower lobe of the lung. On puncture aspiration, the bulla fluid was found to be exudative and contained mostly lymphocytes. A smear examination for acid-fast bacilli was positive, as was polymerase chain reaction (PCR) examination for Mycobacterium intracellulare. Therefore, a diagnosis of infectious lung bulla caused by M. intracellulare was made. A right lower lobectomy was performed. On macroscopic examination of the resected lesion, the area surrounding the bulla was whitish in color, and microscopic examination of this area showed a caseating epitheloid granuloma with acid-fast bacilli. We report this case because there have been no previous reports in the literature of infectious lung bulla caused by M. intracellulare although there have been several reports dealing with lung bulla caused by Mycobacterium tuberculosis.