[Cloacogenic cancer of the rectum].

Three cases of cloacogenous and 35 cases of squamous-cell carcinoma of the distal part of the rectum and anus were studied and compared histochemically to reveal considerable differences in mucopolysaccharides contained by the tumours. Squamous-cell carcinomas were characterized by the presence of glycogen which was not detected in cloacogenous carcinomas. In squamous-cell carcinomas, glycosamine glycanes were represented by sulfo- and sialo-mucin, while cloacogenous carcinomas largely contained a non-sulfated mucosubstance. The evidence obtained allows one to distinguish, among anal carcinomas of the rectum, a group of cloacogenous carcinomas that arose from the transitional epithelium of the serrate line and that differ from squamous-cell carcinomas in specific metabolic processes.