Carcinoembryonic antigen staining in choriocarcinoma.

Choriocarcinoma of the colon presented as life-threatening lower gastrointestinal bleeding and a pathologic femoral fracture in a 42-year-old man. Elevated serum carcinoembryonic antigen (CEA) levels and immunohistochemical positivity for CEA in neoplastic syncytiotrophoblasts were noted, as well as the expected positivity for the beta subunit of human chorionic gonadotropin (beta HCG). Additional cases, including one of two gestational choriocarcinomas and one of four testicular choriocarcinomas studied immunocytochemically for CEA also demonstrated positivity. Although CEA staining is commonly associated with tumors derived from the surface epithelium of the gastrointestinal tract and other organs, its presence in choriocarcinomas should not be interpreted as conclusive evidence of primary origin from these sites.