S4009 Disseminated Mycobacterium Avium Complex With Gastrointestinal Involvement

Introduction: Mycobacterium avium complex (MAC) is known to cause opportunistic infections in immunocompromised individuals but is uncommon in immunocompetent populations. We report a case of MAC infection in an immunocompetent patient with chronic GI symptoms. Case Description/Methods: A 59-year-old man with a history of childhood treated tuberculosis presented to the emergency department with a complaint of abdominal pain. He underwent CT chest/abdomen/pelvis that revealed hepatosplenomegaly with diffuse lymphadenopathy. Axillary lymph node biopsy revealed non-necrotizing granulomatous lymphadenitis. Suspecting sarcoidosis, he was discharged on prednisone but returned with hematochezia and abdominal pain. Repeat CT abdomen/pelvis showed distal small bowel obstruction; subsequent exploratory laparotomy found diffuse adenopathy with extrinsic compression of the jejunum. On jejunal resection, pathology revealed necrotizing granulomatous bowel wall inflammation with numerous mycobacterial organisms. Adjacent lymph nodes demonstrated similar inflammation. The patient started RIPE therapy for extrapulmonary TB. Repeat CT chest after 18 months showed a new mass-like consolidation in the left upper lobe; biopsy showed non-caseating granulomatous inflammation with positive AFB staining for mycobacteria (Figure 1). Follow-up testing was positive for MAC and negative for tuberculosis. He was transitioned to Rifampin, Ethambutol, and Azithromycin. On readmission for recurrent melena and anemia, EGD was unrevealing but antegrade double balloon enteroscopy showed a 6-mm sessile polyp in the duodenal bulb. Biopsy revealed granulation tissue and copious macrophages containing AFBs. Repeat EGD found a large friable 10-mm mass in the distal duodenum that also revealed AFB-containing macrophages. He is awaiting re-evaluation and further recommendations from Infectious Disease for disseminated MAC. Discussion: Disseminated MAC (DMAC) infections can involve virtually every organ system. In the GI tract, DMAC can form ulcers, fistulas, abscesses, and hemorrhage, often characterized by multiple grey-white nodules and papules; our case presented uniquely with large friable masses that bled on biopsy. Given the features of DMAC overlap with other infections such as tuberculosis and Whipple’s disease, this case further illustrates the importance of obtaining multiple biopsies with both AFB staining and genetic testing to determine the type of mycobacteria present.Figure 1.: A: HandE stain of jejunal resection sample; B: AFB stain visualizing mycobacterial organisms.