High iron diamine-alcian blue mucin profiles in benign, premalignant and malignant colorectal disease.

The presence of mucosal hyperplasia and sialomucin goblet cell secretion (transitional mucosa) was assessed in various benign, premalignant and malignant colorectal tissues. Transitional mucosa was seen in diverticular disease, solitary ulcer syndrome of the rectum, ischaemic and irradiation colitis and other diseases including pneumatosis coli, endometriosis, haemorrhoids and a colostomy margin. Adenocarcinomas had a sulphomucin or mixed secretion pattern with transitional features in the adjacent mucosa mucosa (18/27). Premalignant adenomatous polyps showed mixed secretion with transitional glands incorporated in the stalk and sometimes in the adjacent mucosa. Epithelium showing dysplasia secreted sulphomucins and in amounts related to its degree of differentiation. Transitional mucosa may not be a primary premalignant phenomemon. The conclusion and unifying concept is that it is a secondary event related to goblet cell immaturity. This can occur, secondary to proliferation in mucosal inflammation, ischaemia and prolapse or as a phenotypic expression of growth derived from underlying dysplastic epithelium.