Chronic ulcerative colitis may be accompanied by a variety of epithelial changes, including loss of goblet cells, Paneth cell metaplasia, villous metaplasia, and dysplasia. Total colitis is also accompanied by an increased incidence of adenocarcinoma. All these changes are assumed to be secondary to repeated mucosal damage, but how they develop is unknown. Little attention has been paid to the enteroendocrine cell population, despite the postulated role of these cells as producers of trophic hormones. We describe two patients with long-standing ulcerative colitis who developed both adenocarcinoma and carcinoid tumours. In both, there were increased numbers of enteroendocrine cells in the uninvolved colonic mucosa. We suggest that an increased enteroendocrine cell mass may be part of a non-specific reaction to chronic mucosal injury, and by producing an elevated level of trophic hormones may act as a promoter in the development of neoplasia.
SUMMARY Collagenous colitis is a rare condition characterised by watery diarrhoea. It is thought to be caused by a thick collagenous membrane found immediately beneath the colonic surface epithelium. We have studied specimens from 457 patients with a wide variety of large bowel diseases in order to determine the frequency, nature, and clinical correlations of the thick membranes. The normal membrane measured up to 3 microns. In 19 (4%) of the patients studied there was significant thickening (greater than 10 A). In 12 patients the thickening ranged from 10-15 ,u, and six of this group had diarrhoea. In seven, the membrane exceeded 15 ,u, and six patients had diarrhoea. There was no correlation between the nature of the disease process, bleeding, pain, constipation or previous medication. It did not vary with the age, nor at different sites of the colon. We concluded that no case in this series represented an example of true collagenous colitis but that significant thickening of the membrane occurs in other disease conditions and that a thick membrane, no matter how it arises, is causally associated with profuse watery diarrhoea.
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