NCIt definition : A rare, highly malignant epithelial tumor that develops from a hydatidiform mole (50%),
following abortion (25%), or during normal pregnancy (22%). It is characterized by
the presence of invasive and anaplastic trophoblastic tissue composed of intermediate
trophoblastic cells, cytotrophoblasts and syncytiotrophoblasts, abundant vascularity,
and secretion of human chorionic gonadotropin. Because of rapid growth and a high
propensity for hemorrhage, this neoplasm often constitutes a medical emergency.;