A small carcinoma of the rectum with a singular histopathologic feature. Report of a case.

A case of small carcinoma of the rectum with four different histologic types is presented. The carcinoma was a round node (7 X 7 X 2 mm) surrounded by a flat discolored zone (14 X 14 mm) and had four independently different histologic types: well-differentiated adenocarcinoma, adenocarcinoma with microtubular structure, mucinous carcinoma, and signet-ring cell carcinoma. In part of the tumor the direct transition between well-differentiated adenocarcinoma and signet-ring cell carcinoma was seen. The authors believe that the case of rectal carcinoma was a primary form of linitis plastica.