Gestational Trophoblastic Disease: Classification

Gestational trophoblastic disease is a neoplasm that arises from abnormal placental tissue. There are a number of different variants of GTD, the most common types are:

Hydatidiform Moles:  This is the most common type of GTD, which occurs after a woman experiences a miscarriage.  This is otherwise known as molar pregnancy, and happens in about 1 out of 1000 pregnancies in the United States.  These moles are slow growing tumors that look like sacs of fluid, or clusters of grapes on a sonogram.  Hydatiform moles can be complete or partial moles depending upon the makeup of the sperm and egg’s DNA during conception.

Gestational Trophoblastic Neoplasia (GTN): This is a group of GTD that behaves like cancer.  About half of GTN comes from molar pregnancy.  About 25% comes from miscarriages or ectopic pregnancy, and about 25% follows term or preterm pregnancy.  The following are different types of GTN:

  • Invasive moles:  develop from Hydatidiform moles

  • Choriocarcinomas

  • Placental-Site Trophoblastic Tumors (PSTT)

  • Epithelioid Trophoblastic Tumors (ETT)