Inflammatory Polyp in a Pelvic Ileal Reservoir Bryan Warren

Case History: This 59 year old man had a longstanding J-pouch for ulcerative colitis. A polyp was found in the blind limb. The concern: was it neoplastic? Slide 1 Click to view with ImageScope Click to view with a Web-Based Viewer Slide 2 Click to view with ImageScope Click to view with a Web-Based Viewer Pouch pathology is a relatively new area of gastrointestinal pathology. The role of the pathologist is to aid the diagnosis of pouchitis and to exclude and suggest other causes of inflammation within the pouch. The pouch in ulcerative colitis is very different from the pouch in familial adenomatous polyposis. The pouch in FAP will develop adenomas, whereas the pouch in ulcerative colitis will develop (sometimes) pouchitis. Pouchitis is diagnosed by the history of diarrhoea, discharge and systemic upset, the study of diffuse severe inflammation demonstrated endoscopically within the pouch mucosa and the third essential component is histological evidence of both ulceration and severe acute inflammation. All three features may be scored numerically using the Mayo score or the histology alone may be scored using the Shepherd score. The pouch functions as a neorectum and may develop any of the disorders, which one may see within the rectum. This includes secondary pouchitis when there is a source of inflammation outside the pouch and there is a corresponding patch of inflammation in the pouch mucosa this lesion is quite localised. It also includes mucosal prolapse. Mucosal prolapse within the pouch may be present as a red patch, an ulcer or an inflammatory polyp. The polyp seen here is comprised of granulation tissue and the base of the polyp displayed some possible features of mucosal prolapse. Mucosal prolapse features are seen at a staple line anastomosis within the pouch. The likely cause in the case described here, is a granulation tissue polyp (benign inflammatory polyp) related to mucosal prolapse in the pouch. This may be mistaken for neoplasia endoscopically and may need a deep enough biopsy or local endoscopic resection to demonstrate mucosal prolapse changes of muscularisation and diamond shaped crypts. The surface of the polyp may occasionally show serrated architecture suggesting mucosal prolapse. References Blazeby J, Durdey P, Warren BF. Polypoid pouch prolapse in a pelvic ileal reservoir. Gut 1994; 35(11): 1668-1669. Warren BF, Shepherd NA. Surgical pathology of the intestines: The Pelvic ileal reservoir and diversion proctocolitis. In Recent Advances in Histopathology 18, Churchill Livingstone 1999.