[Case of histopathological findings of choriocarcinoma in stomach cancer].

A case of gastric cancer which contained a part of choriocarcinoma was reported in this study. The patient was a 64-year-old man, who was operated on with the diagnosis of gastric cancer in the prepyloric region. The postoperative histological examination revealed that typical choriocarcinoma was noted in a part of the adenocarcinoma, which occupied almost the entire portion of the surgical specimen. In addition, the precise localization of human chorionic gonadotropin (hCG) in the portion of choriocarcinoma was proved by the indirect immunoperoxidase stain (PAP method). The patient showed the gynecomastia clinically. The concentration of postoperative serum hCG was elevated and testicular abnormality was not noted clinically.