Invasive and metastasizing carcinoma in a small adenomatous polyp of the colon: report of a case with demonstration of a tumor associated antigen.

An unusual case of metastasis to two lymph nodes from an adenocarcinoma arising in an adenomatous polyp of the sigmoid colon is presented. Invasion of the stalk could not be detected, but penetration of the muscularis mucosae was observed. Immunoperoxidase staining was used to detect an antigen in the invasive and metastatic components of the tumor that reacted with an antiserum to a tumor associated antigen. A focus of intraepithelial carcinoma was also detected by this method. The relevance of these findings to the adenoma-carcinoma sequence is discussed.