Gestational trophoblastic disease

Gestational trophoblastic disease
Micrograph of intermediate trophoblast, decidua and a hydatidiform mole (bottom of image). H&E stain.
Classification and external resources
Specialty	Oncology
DiseasesDB	2602
MedlinePlus	001496
eMedicine	article/279116
MeSH	D031901
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Gestational trophoblastic disease (GTD) is a term used for a group of pregnancy-related tumours. These tumours are rare, and they appear when cells in the womb start to proliferate uncontrollably. The cells that form gestational trophoblastic tumours are called trophoblasts and come from tissue that grows to form the placenta during pregnancy.

There are several different types of GTD. Hydatidiform moles are benign in most cases, but sometimes may develop into invasive moles, or, in rare cases, into choriocarcinoma, which is likely to spread quickly, but which is very sensitive to chemotherapy, and has a very good prognosis. Gestational trophoblasts are of particular interest to cell biologists because, like cancer, these cells invade tissue (the uterus), but unlike cancer, they sometimes "know" when to stop.

GTD can simulate pregnancy, because the uterus may contain fetal tissue, albeit abnormal. This tissue may grow at the same rate as a normal pregnancy, and produces chorionic gonadotropin, a hormone which is measured to monitor fetal well-being.

While GTD overwhelmingly affects women of child-bearing age, it may rarely occur in postmenopausal women.

Gestational trophoblastic disease (GTD) may also be called gestational trophoblastic tumour (GTT).

Hydatidiform mole (one type of GTD) may also be called molar pregnancy.

Persistent disease; persistent GTD: If there is any evidence of persistence of GTD, usually defined as persistent elevation of beta hCG (see «Diagnosis» below), the condition may also be referred to as gestational trophoblastic neoplasia (GTN).

GTD is the common name for five closely related tumours (one benign tumour, and four malignant tumours):

Here, first a fertilised egg implants into the uterus, but some cells around the fetus (the chorionic villi) do not develop properly. The pregnancy is not viable, and the normal pregnancy process turns into a benign tumour. There are two subtypes of hydatidiform mole: complete hydatidiform mole, and partial hydatidiform mole.

All five closely related tumours develop in the placenta. All five tumours arise from trophoblastic cells. The trophoblast is the membrane that forms the wall of the in the early development of the fetus. In a normal pregnancy, trophoblastic cells aid the implantation of the fertilised egg into the uterine wall. But in GTD, they develop into tumour cells.

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