Disseminated <i>Mycobacterium avium</i> Complex Myositis in a Patient With Graft-Versus-Host Disease

complex (MAC) is a ubiquitous environmental pathogen that was infrequently reported as a cause of disease before the human immunodeficiency virus (HIV)/acquired immune deficiency syndrome epidemic. We present a case of MAC pyomyositis and bacteremia in a 59-year-old man with chronic lymphocytic leukemia in remission after an allogenic stem cell transplant. His posttransplant course was complicated by graft-versus-host disease, requiring treatment with oral steroids and ruxolitinib. In this report, we review the literature on disseminated MAC infection in patients with and without HIV. We also propose a potential mechanism by which this patient may have developed disseminated disease. Disseminated MAC myositis is uncommon in persons without HIV and requires a high index of suspicion for timely diagnosis.