Mycobacterium kansasii infection presenting as cellulitis in a patient with systemic lupus erythematosus

The prevalence of mycobacterial infection has increased in recent years, especially in patients immunocompromised due to autoimmune disease, malignancy and AIDS. Mycobacterium kansasii infection most commonly presents as tuberculosis-like pulmonary disease. We report the case of a 38-year-old woman with systemic lupus erythematosus (SLE) who developed cellulitis over the left lower leg and had poor response to antibiotics. Two months before this admission, she had sustained a small wound over the right pretibial area and had noticed erythematous swelling after swimming at the beach. Pathologic examination of biopsied tissue showed acid-fast bacilli, and culture yielded M. kansasii. The cellulitis improved gradually during treatment with antimycobacterial agents for 1 year. This case emphasizes the possibility that cutaneous M. kansasii infection may occur in an immunocompromised patient and that exposure to contaminated water is a possible source. With early diagnosis, the response to an antimycobacterial multidrug regimen is usually satisfactory.