Aim: Some of the rare complications reported in patients with an ileopouch anal anastomosis (IPAA) after coloectomy for chronic ulcerative colitis are dysplasia and carcinoma. The supposed pathway is for the ileal pouch mucosa to go through adaptational changes then is to progress through the phases of chronic pouchitis, dysplasia and subsequently to adenocarcinoma. In many of these studies however, the dysplasia-cancer sequence is inconclusive since the carcinoma might have developed from the ileal mucosa itself or from residual viable rectal mucosa left behind. The purpose of this study was therefore to study the long-term ileal mucosal adaptation patterns and the incidence and grading of dysplasia in the ileal pouch mucosa in patients previously operated on for ulcerative proctocolitis.
Patients and methods: Forty-five patients who had been operated on with an IPAA (25 males/20 females), with a median age of 54 years (range 34-76), were invited for clinical examination and pouch endoscopy including mucosal biopsies. The duration of their colitis until surgery was median 6 years (range 1-28) and the time median interval from start of disease until time of follow up 24.8 years (range 17-46). Three independent pathologists from two different centres reviewed sequential mucosal biopsies taken from separate sites of the pouch for dysplasia and mucosal adaptation patterns.
Results: The type C pattern with a severe inflammation in lamina propria together with severe atrophy of villi, sometimes with ulceration and granulation tissue, was observed by the two pathologists from one centre in 15 of 45 (33.3%) patients and in 11 (24.4%) of 45 by the third pathologist, respectively. As regards dysplasia one pathologist group evaluated 2/45 (4.4%) cases as low-grade dysplasia while the third pathologist considered one of these cases as indefinite for dysplasia and one as reactive. There was in this respect full agreement between the two centres in 43 (95.6%) of 45 cases. Neither high-grade dysplasia nor invasive carcinoma was diagnosed.
Conclusion: Dysplastic transformation within the ileal pouch mucosa in patients operated for ulcerative proctocolitis is rare even after a long follow-up. These results are reassuring for both patients and surgeons. There seem to be no solid grounds to support routine surveillance for dysplasia in the ileal pouch mucosa in these patients. The surveillance for neoplastic changes in the remaining muscular/epithelial cuff is a separate issue however.