What is GTD?
GTD starts with the growth of tumor cells in the uterus. These cells can grow from several different types of trophoblast cells. These are cells that surround an embryo and become the placenta. The disease is always related to some part of pregnancy.
Half of the time GTD starts with an abnormal pregnancy called a hydatidiform mole. It’s also called a molar pregnancy. Usually the tumor is an abnormal placenta. It develops when an empty egg is fertilized with one or two sperm. When this happens, there can be no baby. The only thing that shows on ultrasound is an abnormal placenta. This is called a complete molar pregnancy.
GTD can also develop from a less common event. When a normal egg is fertilized with two sperm, a fetus develops. But both the placenta and fetus are abnormal. The fetus has three different sets of chromosomes. As a result, it cannot survive. The placenta is full of cysts, when seen on ultrasound, it looks like Swiss cheese. This type of event is called a partial molar pregnancy.
GTD can also start from abnormal cells that grow from remnants of the placenta. Or it can come from a tubal pregnancy or even from what seems to be a normal pregnancy.
GTD always develops from the placenta. As a result, the tumors often make the pregnancy hormone beta hCG. This hormone can serve as a tumor marker that can be used to show response to treatment. Because of the hormone, women often think they are pregnant before the diagnosis. This can be very hard emotionally.
