Adenocarcinoma of the small intestine arising in Crohn's disease. Demonstration of a tumor-associated antigen in invasive and intraepithelial components.

A segment of small intestine surgically removed from a man with intestinal obstruction was found to have coexisting regional enteritis and an invasive adenocarcinoma associated with an area of intraepithelial neoplasia. The cells of the adenocarcinoma and the intraepithelial neoplasia contained a tumor-associated surface antigen capable of reacting with an antiserum prepared against a colonic carcinoma. The importance of thorough sampling of specimens of regional enteritis in accurate reporting of the incidence of carcinoma is stressed, as is the use of immunohistologic techniques as an adjunct to the morphologic diagnosis of preinvasive neoplasia.