Mycobacterium intracellulare causes infection in humans. Involvement of joint and bone, however, is extremely rare. We present the case of an immunocompetent 67-year-old female with chronic swelling of the wrist joint diagnosed as rheumatoid arthritis by her previous physician. Examination revealed an unclosed fistula associated with a puncture, and bone and joint destruction on radiographs. She was diagnosed with osteomyelitis and arthritis due to M. intracellulare on histological and microbiological examinations. She was successfully treated with radical surgical debridement and anti-tuberculous drugs for 1 year and there was no recurrence at 3 years postoperatively.
