Cavitary lung lesion suspicious for malignancy reveals Mycobacterium xenopi

We report the case of a 68-year-old gentleman who presented with musculoskeletal chest pain which appeared suddenly when he bent over with his dog. The chest pain was localized to the left lower chest and increased with movement and deep breathing. The patient did not complain weight loss, night sweat, fever or chill. He complained of mild cough, with expectoration of whitish mucus. Imaging revealed cavitary chest lesion in the right upper lobe, which was initially suspected to be lung cancer. The patient had a 50-year-old history of smoking 2 packs per day. PET CT imaging did not reveal any specific activity. Needle biopsy and bronchoalveolar lavage, however, did not reveal any malignant cells. Rather, necrotic tissues were observed. A wedge resection of the lung mass was performed. No common organisms or fungi could be grown. However, acid fast bacilli were observed in clumps. The morphology hinted towards non-tuberculous mycobacterial organism(s). Molecular studies revealed infection with Mycobacterium xenopi. The patient was started on an anti-tuberculous regimen of INH, rifampicin, ethambutol and PZA, with pyridoxine. The patient is a Vietnam veteran and complained of exposure to dust from a bird's nest and asbestos exposure in childhood, but no specific exposure to tuberculosis. The patient had an uneventful recovery post-surgery. He complained of some nausea after initiation of the antituberculous medications, but his pain subsided with time. The patient had diabetes, though specific reasons of compromise of immune status could not be pinpointed as causative of his nontuberculous mycobacterial lung infection.