A prospective study of dysplasia and carcinoma in the rectal biopsies and rectal stump of eight patients following ileorectal anastomosis in ulcerative colitis.

The present study concerns eight patients with ulcerative colitis treated by total colectomy and ileorectal anastomosis and subjected to follow-up rectal biopsies who later developed precancer (two cases) or carcinoma in the retained rectum. We report the results of the biopsies and the detailed mapping of lesions in the resected rectal stump to highlight certain features which may lead to increased detection rate of early malignancy. Two groups of patients emerged. Group A: in all four cases the follow-up biopsies showed increasing severity of dysplasia; altered mucin secretion with predominance of sialomucins was seen in the biopsies even in the absence of inflammation or dysplasia; the biopsy findings (morphological and secretory) mirrored those observed in the rectal stump; in three, the lesions were villous polypoid growths, of which two were invasive carcinomas. Group B: in none of the cases was dysplasia seen in the biopsies and mucus secretion was normal; similar features were seen in the rectal stump; all had invasive carcinoma of which three were flat ulcerated lesions. The different behaviour of carcinoma in the two groups almost certainly reflects the different tumour phenotype characteristics and this is a matter for further study. From the practical point of view we emphasize the risk of relying on biopsy evidence of dysplasia alone as an indicator of malignancy and the need for additional immunological or histochemical tests to assess the individual risk of cancer in colitis.