S4898 Crohn’s Disease in a Patient With Gardner Syndrome: A Rare Overlap of Two Distinct Entities

Introduction: Gardner syndrome (GS) is a variant of familial adenomatous polyposis (FAP) caused by mutations in the APC gene, associated with near 100% lifetime risk of colorectal cancer without prophylactic colectomy. Though GS includes extracolonic manifestations, it is not known to be associated with inflammatory bowel disease. Distinguishing de novo Crohn’s disease (CD) from post-surgical complications in these patients is diagnostically complex but clinically important. Case Description/Methods: A 22-year-old woman with GS underwent partial colectomy at age 8 and total proctocolectomy with ileal pouch-anal anastomosis at age 11. Her postoperative course was complicated by chronic pouchitis, recurrent anal strictures, and a J-pouch perforation, necessitating permanent ileostomy at age 13. Despite diversion, she continued to experience perianal fistulas and developed extraintestinal manifestations including oral aphthae, erythema nodosum, and peripheral arthropathy. Surgical pathology from resected ileum and rectum showed chronic active inflammation with ulceration and architectural distortion. Resection of the J-pouch also revealed similar features with occasional multinucleated giant cells. Computed tomography enterography demonstrated complex fistulous tracts involving the small bowel, cervix, and perirectal space, along with presacral soft tissue inflammation. The combination of transmural inflammation, fistulizing disease, and extraintestinal findings supported a diagnosis of Crohn’s disease. She was started on infliximab therapy. Discussion: This case highlights the difficulty in diagnosing CD in patients with GS and surgically altered anatomy. Chronic inflammation and fistulization may be misattributed to postoperative sequelae, delaying appropriate management. Histologic features and systemic manifestations can help distinguish CD from surgical complications. Recognition is critical to initiate timely biologic therapy, although immunosuppression must be weighed against the elevated malignancy risk inherent in GS.