(also choriocarcinoma), a malignant tumor of the female genitalia. Chorioepitheliomas arise from trophoblastic elements in young women 25 to 35 years of age, usually after the formation of a hydatiform mole, after abortion, or, less commonly, after childbirth (several years may elapse between the end of the last pregnancy and onset of the disease). The tumor generally originates in the uterus, where it quickly spreads to the uterine wall and hematogenously metastasizes, chiefly to the lungs, brain, and vagina. Symptoms include acyclic uterine bleeding (followed by the development of anemia) and serous leukorrhea. The subsequent course of the disease is determined by development of metastases. The principal causes of death are metastases, profuse bleeding from the uterus and vagina, and cachexia.

The diagnosis of a chorioepithelioma is aided by the detection of uterine enlargement, by the presence of tumor cells in scrapings, and by sharply positive results of an Aschheim-Zondek test using both whole and dilute urine.

Treatment includes the use of drugs (one-third of the patients recover and may later give birth to healthy children), surgery, administration of hormones, and radiation. The principal prophylactic measure is thorough follow-up of patients with a history of hydatiform moles.