Neoplastic transformation of the pelvic pouch mucosa in patients with ulcerative colitis

Background & Aims: Some patients with ulcerative colitis (UC) receiving an ileal pelvic pouch with ileoanal anastomosis (IPAA) develop persistent severe villous atrophy in the pouch mucosa, To investigate if mucosal atrophy indicates a risk for subsequent neoplastic transformation of the ileal pouch mucosa, a follow-up study was undertaken, Methods: Seven patients with UC and an IPAA in whom persistent severe atrophy (type C) developed and 14 control patients with no or only slight atrophy (type A) were prospectively surveyed by flexible videoendoscopy with multiple biopsies for assessment of possible neoplastic changes, Results: The median time of the pouch in function was 9 years for both groups, Dysplasia was found in 5 of 7 patients in the type C group (71%) compared with none in the type A group (P < 0.001), Four patients had low-grade dysplasia, and 1 patient had sequential multifocal development into high-grade dysplasia, Multifocal DNA aneuploidy was found in 2 patients, 1 with low-grade and 1 with high-grade dysplasia, Conclusions: Patients with UC and a long-standing IPAA who develop persistent severe mucosal atrophy ave at risk also of neoplastic transformation of the pouch mucosa.