Gastric choriocarcinoma; an immunohistochemical study.

A case is reported of primary gastric choriocarcinoma occurring in a 73-year-old man, associated with a high serum level of beta hCG. Both primary and lymph node metastases contained exclusively cyto and syncytiotrophoblastic elements. Immunohistochemical localization of chorionic gonadotropin (hCG), placental lactogen (hPL) and pregnancy-specific glycoprotein (SP 1) is described in relation to cytotrophoblastic differentiation. An intramucosal focus of adenocarcinoma supports the hypothesis of the origin of choriocarcinoma from usual gastric cancer.