RESUMO
Approximately 90% of nontuberculous mycobacterium (NTM) infections involve the pulmonary system; NTM infections involving areas of the musculoskeletal system such as the joints or spine are uncommon. This report describes a case of refractory knee swelling in a patient with systemic lupus erythematosus (SLE). Indolent arthritis of the knee eventually progressed to spondylitis and a paraspinal abscess requiring surgical incision and drainage. The cause of the infectious arthritis and spondylitis was diagnosed as NTM infection, specifically Mycobacterium kansasii. This case emphasizes the importance of a high index of clinical suspicion for mycobacterial infection, as well as repeated attempts to isolate the organism, in patients with SLE who present with atypical chronic arthritis.