Mucosal assessment for dysplasia and cancer in the real pouch mucosa in patients operated on for ulcerative colitis -: A 30-year follow-up study

PURPOSE: Sporadic reports of epithelial dysplasia and the occasional development of adenocarcinoma in the ileal pouch mucosa have recently appeared in the literature, pointing toward yet another long-term complication of the continent ileostomy and the pelvic pouch. The incidence of dysplasia and the risk for developing cancer has not been critically evaluated, however, and the reports are contradictory, with most having short observation times. The purpose of this study was to report long-term mucosal adaptation patterns and the incidence of dysplasia in Kock pouches after a mean follow-up of 30 years for patients previously operated on for ulcerative proctocolitis. METHODS: Two sets of two pathologists each (in Gothenburg, Sweden, and Manchester, United Kingdom) examined sequential, small-intestinal biopsy specimens from 40 patients with Kock pouch to observe long-term epithelial changes, with particular reference to the presence of dysplasia. RESULTS: There was full agreement between the two groups regarding the absence of high-grade dysplasia and invasive carcinoma (Categories 4 and 5 of the Vienna classification). There was, however, significant disagreement in reporting the frequency of low-grade and indefinite categories of dysplasia (Categories 2 and 3, of the Vienna classification). No attempt was made to report the differences within each set of pathologists. CONCLUSION: Because no case of high-grade dysplasia or invasive carcinoma was found in this study after a mean follow-up of 30 years, we conclude that it is very unlikely for invasive carcinoma to be a complication in ileal pouch mucosa.