Just Deep to the Surface: An Ever-Present Danger of Mycobacterium Avium Complex


ENS Michael Groden, Uniformed Services University of the Health Sciences, Bethesda, MD, LCDR Laura Gilbert, MD, Walter Reed National Military Medical Center, Bethesda, MD, LT Tyler Church, DO, Walter Reed National Military Medical Center, Bethesda, MD, LTC Jason Blaylock, MD, Walter Reed National Military Medical Center, Bethesda, MD.


Non-tuberculous mycobacterium (NTM) are ubiquitous in the environment and infections from these organisms are increasingly recognized. In particular, Mycobacterium avium complex (MAC) has garnered interest because of its capability of causing disseminated disease in AIDS patients and severe pulmonary infections in immunocompetent hosts. We present a rare case of disseminated soft-tissue MAC infection in an individual presenting with panniculitis while on minimal immunosuppression for an underlying rheumatologic disease.

Case Presentation

A 34-year-old HIV-negative African American female with well-controlled dermatomyositis on low-dose daily prednisone and azathioprine for over three years presented with three months of night sweats and unintentional weight loss in the setting of new right tibial and deep right posterior thigh nodules. Biopsies performed at the two areas revealed panniculitis (deemed secondary to dermatomyositis) and her immunosuppression was not changed. The patient's symptoms worsened, and further imaging showed multiple large soft-tissue fluid collections of the right and left posterior thighs concerning for abscesses, prompting surgical irrigation and debridement. Multiple deep wound cultures demonstrated MAC (susceptible to clarithromycin) and whole-body imaging showed no additional lesions. A prior bronchoscopy failed to reveal AFB organisms in bronchoalveolar lavage specimens. She was diagnosed with disseminated soft-tissue MAC and started on ethambutol, azithromycin, and rifampin. Her treatment course was complicated by initial recurrence of bilateral thigh abscesses requiring multiple debridements and discontinuation of rifampin due to debilitating “flu-like” side effects. The patient declined recommendations for addition of aminoglycosides and aggressive surgical debridement. After consultation with national mycobacterial experts, clofazimine was added to her regimen. After six months of treatment, she continues to tolerate the antibiotic regimen well and has notable decrease in size of the remaining abscesses.


MAC is the most common NTM and is known to present as an opportunistic infection in immunocompromised patients. We describe an unusual presentation of disseminated MAC without pulmonary involvement in a minimally immunocompromised patient. This is the second documented case of a patient with an underlying rheumatologic condition presenting with panniculitis and found to have disseminated MAC. Treatment guidelines for disseminated MAC infections are extrapolated from pulmonary guidelines which recommend polymicrobial therapy to include a macrolide backbone for at least 6 months. Rarely, adjunct therapies are needed due to intolerable side effects of first-line regimens and difficulty in obtaining complete eradication. Clofazimine is FDA-approved for leprosy but has an indication for severe MAC infections; however, in the US this can only be obtained via compassionate use IND. This case illustrates the importance of not only maintaining a broad differential in immunocompromised patients presenting with skin manifestations with even minimal immunosuppression but also highlights the importance of future research to help guide treatment for disseminated MAC infections and a need for increased awareness of atypical presentations.

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