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. (J Rheum Dis 2016;23:66-70)

Keywords: Nontuberculous mycobacteria, Systemic lupus erythematosus