Immunohistochemical localization of thrombomodulin in chorionic diseases of the uterus and choriocarcinoma of the stomach. A comparative study with the distribution of human chorionic gonadotropin.

Thrombomodulin (TM) is a newly described protein that functions as a potent natural anticoagulant by converting thrombin from a procoagulant protease to an anticoagulant. TM is found on endothelium of the blood and lymph vessels and on syncytiotrophoblast of the placenta in humans. In the current study, we localized TM by immunohistochemistry in chorionic diseases of the uterus and choriocarcinomas of the stomach. The syncytiotrophoblast of hydatidiform mole contained TM. Uterine choriocarcinoma also had TM in the neoplastic syncytiotrophoblastic cells, although some of the neoplastic syncytiotrophoblastic cells showed no TM expression. Gastric choriocarcinoma never showed TM expression in the neoplastic syncytiotrophoblastic cells. However, all of the syncytiotrophoblastic cells had human chorionic gonadotropin (hCG) in hydatidiform mole, uterine choriocarcinoma, and gastric choriocarcinoma.