A group of diseases originated from placental trophoblastic cells Gestational trophoblasitc disease (GTD) Hydatidiform mole (complete and partial) Invasive mole Choriocarcinoma Placental-site trophoblastic tumor (PSTT) Gestational trophoblastic neoplasia (GTN) Non-gestational trophoblastic tumor Uncommon, derived from germ cells in ovarian or testicular