A rare cancer in women of childbearing age in which cancer cells grow in the tissues that are formed in the uterus after conception. Also called gestational trophoblastic tumor, gestational trophoblastic neoplasia, molar pregnancy, or choriocarcinoma.

mainly as a Hydatidiform Mole, (though there can be non-hydatidiform forms) tumour with "grape-like" placental appearance without enclosed embryo formation, arises mainly from a haploid sperm fertilizing an egg without a female pronucleus. (More? Week 1 Abnormalities | Week 2 Abnormalities)

An abnormal pregnancy with a cystic growth of the placenta hydatid mole develops from the trophoblastic tissue of the early embryonic stage of development. With gestational trophoblastic disease all of the usual signs are highly exaggerated. The growth of the uterus is unusually rapid, morning sickness is often severe and there are high levels of chorionic gonadotropin as well as high blood pressure. In such cases the uterus must be evacuated to prevent the mole from developing into choriocarcinoma. Often abbreviated to GTN or called a molar pregnancy.