GTN typically arises after a molar pregnancy, but it can also develop after any type of pregnancy, including normal pregnancies, miscarriages, and ectopic pregnancies. The abnormal trophoblastic cells proliferate uncontrollably, leading to tumor formation. A molar pregnancy is characterized by the presence of a mole that forms instead of a normal embryo. If untreated, these abnormal cells can invade the uterine wall and, in some cases, spread to other parts of the body.
