trophoblastic tumor, gestational

trophoblastic tumor, gestational A tumor of women, which develops in the tissues that are formed following conception by the joining of sperm and egg. Gestational trophoblastic tumors start inside the uterus, the hollow, muscular, pearshaped organ where a baby grows. This type of tumor occurs in women during the years when they are able to have children. There are two types of gestational trophoblastic tumors: hydatidiform mole and choriocarcinoma.