SHM Converge Scientific Abstract ePoster Gallery-Mac or Autoimmune Attack?

Pdf Summary

The case describes a patient initially thought to have an autoimmune flare or worsening inflammatory myopathy because of multifocal joint involvement and persistent fluid collections. Rheumatology was consulted due to concern for a noninfectious inflammatory process. However, imaging of the right shoulder showed findings consistent with septic arthritis and osteomyelitis, including extensive joint effusion, abscesses, and osteomyelitis involving the humerus, clavicle, and scapula, with associated pyomyositis.

The diagnosis became clearer when cultures from a prior hospitalization returned during the current admission and identified <strong>Mycobacterium avium-intracellulare (MAC)</strong>. Additional targeted sampling for acid-fast bacilli was positive from the <strong>right shoulder</strong> and <strong>left ankle</strong>, confirming disseminated mycobacterial infection rather than an autoimmune disease flare.

The patient was ultimately started on <strong>rifampin, azithromycin, and ethambutol</strong>, the standard multidrug regimen for MAC infection.

Overall, the case highlights how disseminated MAC can mimic autoimmune or inflammatory musculoskeletal disease, especially when multiple joints and soft tissues are involved. Imaging and culture data were essential in distinguishing infection from autoimmune progression.

Asset Subtitle

Andrew Cuyegkeng

Meta Tag

Author List Andrew Cuyegkeng, Harshal Mehdi, Yan Xing

Category Clinical Vignettes

Concept Disseminated infection

Concept Musculoskeletal Infection

Concept Mycobacterium avium complex

Concept Nontuberculous mycobacteria

Concept Rim-Enhancing Collection

Distinguished Non-Finalist

Presenter Organization UC San Diego Health

Presenting Author Andrew Cuyegkeng

Track Adult

Keywords

Mycobacterium avium-intracellulare

disseminated MAC infection

septic arthritis

osteomyelitis

pyomyositis

autoimmune flare

inflammatory myopathy

right shoulder

left ankle

rifampin azithromycin ethambutol

Disseminated infection

Musculoskeletal Infection

Mycobacterium avium complex

Nontuberculous mycobacteria

Rim-Enhancing Collection