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Trophoblastic Disease

The gestational trophoblastic diseases include the hydatidiform moles, invasive moles, choriocarcinoma, and placental site trophoblastic tumor. The latter three of these are often termed gestational trophoblastic tumors because the decision to institute treatment is often undertaken without a precise histologic diagnosis. I would like to discuss the pathology of these, their incidences, their clinical presentation, how we categorize or classify these patient’s and how we decide to treat the patient’s based on their clinical classification and the outcome of treatment and subsequent pregnancy outcomes. Hydatidiform moles and abnormal pregnancy, that is why I am talking to you today is in this section.

We now recognize that there are two syndromes of hydatidiform mole complete or classic mole and partial mole, this is an example of a complete hydatidiform mole that has been well preserved because this patient elected to have treatment by hysterectomy which isn’t ordinarily the case. You can see this large, placental mass with large hydropic grossly dilated villi. It appears as though the origin of complete mole is fertilization of an empty egg. A 23 X sperm fertilizes an egg in which the genetic material is either absent or does not participate in the reproductive process by some means. Once fertilization occurs, the hapway chromosome complement of the sperm then replicates itself, so you end up with a 46 XX mole.

The other syndrome is a partial mole, as the name implies, a portion of the placenta has these same hydropic molar changes or these changes are less complete throughout the entire placenta. You will see that there is either a fetus or fetal red blood cells or fetal membranes that can be identified in partial mole. Here we have a partial mole where a portion of the placenta has these same hydropic changes and over here is a fetus. The fetus is always abnormal if there is one present in a partial mole.

The chances of a partial mole requiring further treatment after evacuation are somewhere around 5 to 10%, so these patient’s need to be followed exactly the same way that a complete mole is followed after evacuation. Microscopically, you see the big hydropic villous here, no blood vessels, central cistern formation, trophoblastic proliferation around the entire circumference.

As I said, after evacuation of the molar pregnancy, you can get initial fall of the hCG levels and then a plateau will arise and this is indicative or probably the tumor has grown into the wall of the uterus and is persisting, and that’s called invasive mole, we don’t very often make the diagnosis histopathologically anymore because we end up treating these patient’s based on a clinical presentation of a plateau or a rise in the hCG after initial fall as well as continued enlarged uterus, uterine bleeding. This occurs around somewhere around 10 to 17% of patient’s who have a molar pregnancy.

This is what this looks like, there is a big tumor in the upper portion of the uterus, there is only hemorrhage in the cavity of the uterus, not out in the periphery of the tumor and microscopically, these intermediate trophoblasts here monocellular pattern grow in between them on the myometrial smooth muscle cells. Hydatidiform mole occurs in the United States about one in every 1500 to 1000 pregnancies, and certain parts of the world, such as the far east and Mexico it occurs more frequently.

Classically, what you read in your text books, it appeared that almost all patient’s who have molar pregnancy present with abnormal bleeding in the late first trimester, early second trimester of pregnancy and as many as 50% or more will have uterine enlargement. It was also thought that about a quarter of patient’s presented with toxemia or hyperemesis, it turns out that now a days with earlier diagnosis with the use of ultrasound, the minority of patient’s will actually have uterine enlargement.

Once you have made the diagnosis of a hydatidiform mole, you need to evacuate the mole from the patient. There are two ways to do that, one is by suction evacuation and curettage, the other is by hysterectomy. There is no place for medical induction of labor in patient’s who have molar pregnancy for evacuation, it increases the maternal morbidity at the time and also increases the risk of developing postmolar gestational trophoblastic tumor. It does make any difference how big the uterus is, you can do this usually under paracervical block now a days and simply by dilating the cervix and using a suction curette.

We advise contraception for at least six months if their hCG returns to normal, birth control pills are good, they suppress LH which may interfere with measurement of hCG at low levels and there is no relationship with the use of oral contraceptive pills and the development of postmolar gestational trophoblastic tumor. If the hCG levels plateau for three consecutive weeks, or rise for two consecutive weeks, or if the hCG level is greater than 20,000 units four weeks after evacuation of if the hCG.

Other people have found the same sort of thing, Donald Goldstein at Harvard treated 20% of the patient’s at the New England Trophoblastic Disease Center after molar evacuation, Currie and Hammod at Duke treated 20% of their patient’s. If you use hCG regression curves, you will treat more patient’s, if they fall off the regression curve, but you can’t cure any more than 100% and in England, they did not treat patient’s if their hCG plateaued, they only treated patient’s through HG Rose and we know that invasive mole tends to undergo spontaneous regression and if they follow patient’s far enough, they end up fewer patient’s.