Keck School of Medicine of the University of Southern California Los Angeles, CA, United States
Award: Presidential Poster Award
Lillian Dawit, MD1, Prachi Nene, MD1, Ling Shao, MD, PhD2 1Keck School of Medicine of the University of Southern California, Los Angeles, CA; 2University of Southern California, Los Angeles, CA
Introduction: Disseminated Mycobacterium avium complex (MAC) is a rare disease that predominantly arises in immunocompromised patients. The disease can mimic other systemic pathologies making it challenging to diagnose. We present a case of intestinal MAC infection in an immunocompetent woman initially presenting with diffuse lymphadenopathy and a cecal mass.
Case Description/Methods: A 51-year-old Chinese woman with no known prior medical history presented to an emergency room with diffuse pruritus, weight loss, and the development of several lumps in her neck over three months. On arrival, she was tachycardic, and noted to have bilateral cervical lymphadenopathy with overlying firm, erythematous, indurated plaques. Labs were notable for a leukocytosis to 25.9 K/cumm, hemoglobin of 9.5 g/dL, and calcium of 15.0 mg/dL. She denied any fevers, recent travel, or history of intravenous drug use.
A CT Abdomen showed diffuse intra-abdominal and hilar lymphadenopathy and a circumferential mass-like wall thickening of the cecum. A colonoscopy was subsequently performed and revealed extensive carpeted polypoid mucosal thickening in the cecum (Image 1), with pathology from the cecal biopsy showing active chronic inflammation extending into the submucosa, crypt loss, and numerous ill-defined non-necrotizing epithelioid cell granulomas. Given the patient's diffuse lymphadenopathy, hypercalcemia, skin findings, and granulomas on biopsy, there was concern for tuberculosis. Thus, RIPE therapy was initiated for empiric tuberculosis treatment, pending further culture data.
One month later, the acid-fast bacilli culture of the cecal biopsy resulted with speciation of Mycobacterium avium-intracellulare complex, confirming intestinal nontuberculous mycobacterial (NTM) infection. The patient was continued on antimicrobial therapy with close follow-up in the infectious disease clinic.
Discussion: This is the first reported case of intestinal MAC infection in an immunocompetent patient. Mycobacterium avium-intracellulare complex is an NTM species which most commonly infects the lungs. Extrapulmonary, or disseminated, MAC primarily occurs in severely immunocompromised individuals and can manifest in the lymphatic system, bone, liver or gastrointestinal tract. Early initiation of antimicrobial therapy is vital to reduce morbidity and mortality. As most research is specific to immunocompromised individuals, this case demonstrates the need for additional research regarding incidence, treatment, and outcomes in immunocompetent patients.
Figure: Colonoscopy image showing extensive carpeted polypoid mucosal thickening in the cecum
Disclosures: Lillian Dawit indicated no relevant financial relationships. Prachi Nene indicated no relevant financial relationships. Ling Shao indicated no relevant financial relationships.
Lillian Dawit, MD1, Prachi Nene, MD1, Ling Shao, MD, PhD2. P0217 - A Rare Case of Intestinal Mycobacterium avium Complex Infection in an Immunocompetent Host, ACG 2021 Annual Scientific Meeting Abstracts. Las Vegas, Nevada: American College of Gastroenterology.