Background mucosal changes in colorectal carcinomas.

The entire colonic mucosa of 51 cases of colorectal carcinoma was examined histologically. Mucosal lesions including goblet cell hyperplasia, crypt dilatation, ulceration with regeneration, basal cell hyperplasia, metaplastic lesions, and adenomas were encountered. Goblet cell hyperplasia (80.4%) was most prominent adjacent to the carcinoma (transitional mucosa). Whether this represents a precancerous change is controversial. Crypt dilatation (57%) is considered a nonspecific change due to mucosal injury and indicates obstruction to the outlet of the crypts. Ulceration (6%) is often proximal to the carcinoma and is considered secondary to stasis and ischaemia due to obstruction. Basal cell hyperplasia is particularly prominent at the site of lymphoid follicles. It is suggested that the hyperplasia is a reactive response to the presence of stimuli in the intestinal content. It is observed that metaplastic lesions have their origin from these foci of basal cell hyperplasia. The presence of basal cell hyperplasia in metaplastic polyps (14%) indicates that they are active lesions in the process of formation and growth. The occurrence of metaplastic lesions may provide an indication of an adverse environment and a vulnerable mucosa. Adenomas have their origin from basal cells of colonic crypts. They are present in 47% of colorectal carcinoma. The findings support the view that adenomas are the most common and important precursor lesion associated with colorectal carcinoma in man. No de novo foci of malignant transformation was encountered but this does not exclude the possibility of de novo carcinogenesis of the colorectum.