alpha-Fetoprotein-producing rectal carcinoma--a case report.

A case with an alpha-fetoprotein (AFP)-producing carcinoma originating from the rectum is described. A 71-year-old male patient, who underwent a rectectomy for rectal carcinoma, developed space occupying lesions in the liver and a remarkable AFP elevation (220,000 ng/ml) in the 6th month postoperatively, and then expired one year later. Histologically, the rectal carcinoma consisted of well-differentiated adenocarcinomas, and contiguous cancerous cells proliferating in either a medullary or trabecular pattern. In the "trabecular" areas, localization of AFP was confirmed immunohistochemically. Results of concanavalin A or lens culinaris agglutinin affinity chromatography demonstrated that it was between a hepatic type and a yolk sac type, and was considered to be an intestinal type. This could have been an AFP-producing rectal carcinoma, in which the patient experienced liver metastasis at a relatively early postoperative period and died. This shows that AFP-producing rectal carcinomas are highly malignant, biologically, similar to AFP-producing gastric cancers.