|What causes it?|
|A hydatidiform or invasive mole occurs when a single sperm fertilizes an egg without a nucleus. The chromosomes in the sperm duplicate, resulting in an abnormal embryo that has only male genetic material. A mole can also occur when two sperm fertilize a single egg. A mole develops from the abnormally fertilized egg and is characterized by a lack of a normal fetus and by many small fluid-filled cysts.|
The cause of choriocarcinoma is uncertain. It can arise from a normal pregnancy, a miscarriage, a tubal pregnancy or from either type of mole. A interesting statistic is that GTD is the most common in the Philippines and Taiwan.
|How it spreads?|
|A hydatdiform mole generally stays confined to the endometrial cavity. When it begins to invade the wall of the uterus, it is called an invasive mole.|
An invasive mole can penetrate the full thickness of the uterine wall and rupture, resulting in severe internal or vaginal bleeding. Invasive moles can also spread to other organs, most commonly to the vagina and lung. This may be confusing since women with proven invasive moles who have metastases may also have choriocarcinoma. Although an invasive mole is locally more aggressive than a noninvasive mole, it is no more likely to be complicated by choriocarcinoma.
Choriocarcinoma can spread virtually anywhere in the body but most commonly spreads to the lung, the lower genital tract (cervix, vagina and vulva), the brain, the liver, kidney and the gastrointestinal tract.
|Gestational trophoblastic disease occurs only in women of reproductive age. An invasive mole develops in 10 to 20 percent of all complete moles. Choriocarcinoma develops in 3 percent of complete moles but rarely in partial moles.|
At significantly higher risk:
Risk for the development of a hydatidiform or invasive mole or choriocarcinoma include:
For women with a molar pregnancy, there are several risk factors associated with the subsequent development of an invasive mole and choriocarcinoma. These include delayed hemorrhage after the mole is removed in a dilation and curettage (D&C) procedure, large ovarian (theca-lutein) cysts, acute respiratory failure at the time of the D&C, a large uterus before the D&C, a serum BHCG level greater than 40,000 mlU/mL, a history of a previous mole and maternal age over 40.
|Since it is so rare, GTD is not routinely screened for. It is reasonable, however, to perform an ultrasound examination early in any subsequent pregnancy for women with prior GTD.|
Common signs and symptoms:
A molar pregnancy is usually associated with bleeding in the first half of a pregnancy, an absent fetal heartbeat, pain in the lower abdomen, and occasionally with high blood pressure before 24 weeks of pregnancy, excessive nausea or vomiting, a uterus larger than normal for the gestational age (50 percent of all cases) and the expulsion of cysts.
Eighty to 90 percent of women with partial moles have abnormal uterine bleeding, a smaller than expected uterus for the gestational age of tae pregnancy or the signs and symptoms of a spontaneous abortion. The most common symptoms of choriocarcinoma are lack of a menstrual period, symptoms of pregnancy, abnormal vaginal bleeding or pelvic pain. Women with liver metastases may have bleeding within the abdomen because of a ruptured liver. Those with metastases to the lung may have a dry cough, cough up blood and have chest pain or shortness of breath. Spread to the intestinal tract may be associated with chronic blood loss and anemia or with massive hemorrhage. Brain metastases are often associated with symptoms that suggest a brain tumor or stroke.
|The diagnosis is usually suspected after an ultrasound examination of the uterus, but absolute diagnosis of a mole is made by examining the cysts under a microscope. A serum BHCG level far in excess of that of a normal pregnancy would support the diagnosis of a hydatidiform mole.|
An invasive mole is seldom diagnosed definitively without a hysterectomy. The diagnosis is usually suggested after a hydatidiform mole is removed and the BHCG titers remain elevated and there is no evidence of metastases. It is more properly referred to as nonmetastatic (if confined to the uterus) trophoblastic disease (NMTD).
Confirmation of choriocarcinoma by removing cells for pathological analysis is not required and may be hazardous since their tumor bleeds easily.