S4918 Granulomas, Gut, and Granulocyte Dysfunction: Adult Onset CGD Masquerading as Crohn’s

Introduction: Chronic granulomatous disease (CGD) is a rare primary immunodeficiency caused by mutations in the NADPH oxidase complex, with an incidence of approximately 1 in 250,000 individuals. Although CGD typically presents in childhood, adult-onset cases occur and can mimic inflammatory bowel disease (IBD). Notably, IBD affects nearly one-third of patients with CGD. Differentiating CGD-associated colitis from Crohn’s disease or ulcerative colitis is diagnostically challenging but crucial, as treatment strategies differ significantly. Case Description/Methods: A 46-year-old man presented with chronic diarrhea and was diagnosed with ulcerative colitis. After failing budesonide, colonoscopy revealed granulomas, and Crohn’s disease was diagnosed. He improved on adalimumab but later developed fevers and weight loss. Imaging showed hepatic abscesses growing methicillin-susceptible Staphylococcus aureus. Despite intravenous cefazolin and drainage, fevers persisted. Recurrent infections raised concern for CGD, confirmed by oxidative burst testing. Prednisone led to rapid improvement, and he was started on prophylactic antibiotics and antifungals. Gastrointestinal symptoms recurred during steroid taper. Colonoscopy showed patchy colitis and granulomas. Vedolizumab was initiated for suspected CGD-IBD. After 2 doses, he developed severe abdominal pain and high-output diarrhea. Imaging showed worsening hepatic abscesses. Biologic therapy was stopped, abscesses drained, and antibiotics restarted, leading to clinical improvement. Hematopoietic stem cell transplantation is now being considered with hematology. Discussion: This case highlights the challenge of distinguishing CGD colitis from Crohn’s disease in adults. Key signs like persistent fever, granulomas, and recurrent liver abscesses should raise suspicion for CGD. Early diagnosis is critical to avoid harmful immunosuppression. While corticosteroids may help, relapse is common, and biologics increase infection risk. Hepatic abscesses need antibiotics and drainage. Hematopoietic stem cell transplantation is the only cure and should be considered for severe cases. Effective management requires a multidisciplinary approach to balance infection control with inflammation treatment.