Non-cancerous gestational trophoblastic disease

A non-cancerous (benign) tumour is a growth that doesn’t spread (metastasize) to other parts of the body. Non-cancerous tumours are not usually life-threatening. They are typically removed with surgery and don’t usually come back (recur).

Hydatidiform mole is the most common type of non-cancerous gestational trophoblastic disease (GTD). Atypical placental site nodules and exaggerated placental site reactions are very rare.

There are 2 types of hydatidiform mole.

Partial hydatidiform moles develop when 2 sperm fertilize an egg. This means that the embryoblast has an extra set of DNA from the father. A fetus may begin to develop, but it will usually result in a miscarriage within the first trimester. In very rare cases, a normal fetus can develop alongside the hydatidiform mole. When this happens, the hydatidiform mole is treated after the baby is born.

Complete hydatidiform moles develop when a sperm fertilizes an egg that doesn’t have the mother’s DNA (called an empty egg). As a result, a fetus can’t develop because the embryoblast only has DNA from the father.

Both types of hydatidiform mole are usually treated with dilation and curettage (D&C) to remove the abnormal tissue from the uterus. Sometimes a second D&C is needed if some abnormal tissue remains. A hysterectomy may be done to reduce the chance that a cancerous type of GTD will develop in the uterus.

In rare cases, a hydatidiform mole can develop into cancer. Partial hydatidiform moles are less likely to come back after they are removed or to become cancer than complete hydatidiform moles.

Very rarely, small amounts of tissue from the placenta will stay in the uterus after pregnancy. Atypical placental site nodules can develop from trophoblast cells in this tissue. They usually develop in the inner layer of the uterus (called the endometrium). Sometimes they occur in the cervix. In rare cases, atypical placental site nodules can develop in a fallopian tube or an ovary.

Atypical placental site nodules can be hard to diagnose because they cause different symptoms than other types of GTD. Symptoms can include irregular menstrual cycles, abnormal Pap test results and bleeding after sex.

Sometimes atypical placental site nodules can develop alongside an epithelioid trophoblastic tumour (ETT) or a placental site trophoblastic tumour (PSTT). It is also possible for an atypical placental site nodule to turn into ETT or PSTT.

Atypical placental site nodules are usually removed with dilation and curettage (D&C) or a hysterectomy.

An exaggerated placental site reaction is a tumour that starts in the trophoblast. It can grow through the inner lining of the uterus (called the endometrium) into the muscle wall of the uterus (called the myometrium).

This type of GTD usually doesn’t cause any symptoms. Sometimes exaggerated placental site reaction can cause vaginal bleeding early on in pregnancy or heavy bleeding after childbirth. It can be found during a D&C done after a miscarriage to remove any remaining trophoblast tissue.

Exaggerated placental site reaction is very rare. Researchers continue to study this type of GTD to find better ways to diagnose and treat it.