Polyembryoma is a rare, very aggressive form of germ cell tumor usually found in the ovaries.
It has been found in association with Klinefelter syndrome.[1]
Embryonal carcinoma
Mesonephroma: Endodermal sinus tumor/Yolk sac tumor
Teratoma: Fetus in fetu · Dermoid cyst · Struma ovarii
Trophoblastic neoplasm: Gestational trophoblastic disease (Hydatidiform mole) · Choriocarcinoma
Polyembryoma