Histopathological Evaluation of Pouch Neoplasia in Inflammatory Bowel Diseases and Familial Adenomatous Polyposis

BACKGROUND: Ileal pouch-anal anastomosis is often required for patients with ulcerative colitis or familial adenomatous polyposis after colectomy. This procedure reduces but does not completely eliminate the risk of neoplasia. OBJECTIVE: This study focuses on the histopathology of neoplasia in the ileal pouch, rectal cuff, and anal transition zone. DATA SOURCES: We performed a Medline search for English language studies published between 1981 and 2022 using the PubMed search engine. The terms “ileal pouch-anal anastomosis,” “pouchitis,” “pouch dysplasia,” “pouch lymphoma,” “pouch squamous cell carcinoma,” “pouch adenocarcinoma,” “pouch neoplasia,” “dysplasia of rectal cuff,” and “colitis-associated dysplasia” were used. STUDY SELECTION: Human studies of neoplasia occurring in the pouch and para-pouch were selected and the full text was reviewed. Comparisons were made within and across studies, with key concepts selected for inclusion in this manuscript. CONCLUSIONS: Neoplasia in the pouch is a rare complication in patients with ileal pouch-anal anastomosis. Annual endoscopic surveillance is recommended for familial adenomatous polyposis patients and UC patients with a history of prior dysplasia or carcinoma. In familial adenomatous polyposis, dysplastic polyps of the pouch are visible and readily amenable to endoscopic removal; however, glandular dysplasia in the setting of ulcerative colitis may be invisible on endoscopy. Therefore random biopsies and adequate tissue sampling of the pouch and rectal cuff are recommended in this setting. The histological diagnosis of inflammatory bowel disease-associated dysplasia can be challenging and should be confirmed by at least one expert gastrointestinal pathologist. See video from symposium.