Gestational trophoblastic disease (GTD) is usually identified as a hydatidiform mole (a molar pregnancy) or as gestational trophoblastic neoplasia (GTN). Each disease is categorized into various subtypes.Molar pregnancies
Hydatidiform moles are divided into two subtypes:
Complete molar pregnancy: This occurs when the sperm fertilizes an egg that doesn’t contain the woman’s DNA or a nucleus, causing the tissue to form a mound of abnormal cells instead of a fetus. Complete molar pregnancies are typically slow to grow, and most of the time, they are noncancerous, though they are more likely to become cancerous than partial molar pregnancies.
Partial molar pregnancy: This condition develops when the egg is fertilized by two sperms, resulting in two sets of the male’s DNA. Part of a fetus may form in a partial molar pregnancy, but it cannot fully develop.Gestational trophoblastic neoplasia (GTN)
GTNs are typically cancerous. The types of GTNs include:
Invasive mole, which is a type of molar pregnancy that has the potential to metastasize. They may grow into the muscle layer of the uterus.
Choriocarcinoma, which is a cancerous tumor that may grow quickly and spread to the muscle layer of the uterus, the blood or organs outside the uterus. Choriocarcinomas make up about 5 percent of all GTDs.
Placental-site trophoblastic tumors (PSTT), which is a rare form of GTN that forms where the placenta meets the uterus. These tumors grow slowly, but they may spread to the muscle layer of the uterus, the blood, the lymph nodes, the pelvis or the lungs.
Epithelioid trophoblastic tumors (ETT), which may spread to the lungs. These tumors are the rarest of all GTNs.
Learn more about treatments for gestational trophoblastic disease
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