Persistent trophoblastic disease is when women who have had treatment to remove a molar pregnancy from the womb still have some molar tissue left behind. This occurs in about 1 in 12 women (8%) after a molar pregnancy.
A molar pregnancy occurs when the fertilisation of the egg by the sperm goes wrong and leads to the growth of abnormal cells or clusters of water filled sacs inside the womb. Only about 1 in every 590 pregnancies in the UK is a molar pregnancy. This condition is one of a group of conditions known as gestational trophoblastic disease (GTD).
Even a very small amount of molar tissue anywhere in the body can grow and cause problems. Persistent trophoblastic disease can spread to other parts of the body like a cancer but it has a cure rate of nearly 100%.
The treatment for persistent trophoblastic disease is usually chemotherapy.
A choriocarcinoma is a cancer that happens when cells that were part of a normal pregnancy or a molar pregnancy become cancerous. It can happen after a full term pregnancy, miscarriage, ectopic pregnancy or abortion.
Choriocarcinoma only happens in about 1 in every 50,000 pregnancies and there are fewer than 20 cases a year in the UK. It is usually curable.
Chorio refers to the word chorion, which is the outer covering (membrane) of the growing baby (foetus). Carcinoma means a cancer in the epithelial cells which cover or line a body organ.
Where these conditions start
Persistent trophoblastic disease and choriocarcinomas are most commonly found in the womb but they can spread to other areas of the body and might cause symptoms there.
Choriocarcinoma can develop some months or even years after pregnancy and can be difficult to diagnose, because it is so unexpected. They can grow quickly and might cause symptoms within a short period of time. They can spread to other parts of the body but are very likely to be cured by chemotherapy treatment.