Primary choriocarcinoma of the urinary bladder in association with undifferentiated carcinoma.

A carcinoma of the urinary bladder with a distinct choriocarcinomatous component that developed in a postmenopausal woman was associated with high titers of circulating chorionic gonadotropin. The diagnosis was supported by histochemical demonstration of human chorionic gonadotropin in syncytial tumor giant cells and electron microscopic features consistent with syncytiotrophoblastic cell differentiation.