G estational T rophoblastic - PowerPoint Presentation

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Gestational Trophoblastic Disease(GTD) Molar Pregnancyby: Dr.Maryam Aghdaki GYN Oncology Fellowship

INTRODUCTIONMolar pregnancy is part of a group of diseases classified as gestational trophoblastic disease (GTD), which originate in the placenta and have the potential to locally invade the uterus and metastasize. The pathogenesis of GTD is unique because the maternal tumor arises from gestational rather than maternal tissue .HM is made up of two distinct entities, complete HM and partial HM. These differ on the basis of chromosomal pattern, gross and microscopic histopathology, clinical presentation, and outcome. Molar pregnancies, although benign, are considered to be premalignant because they have the potential to develop into a malignancy. Malignant disease is referred to as gestational trophoblastic neoplasia (GTN); the histologic entities included in this group are:●Invasive mole●Choriocarcinoma●Placental site trophoblastic tumor (PSTT)●Epithelioid trophoblastic tumor (ETT)

COMPLETE HYDATIDIFORM MOLEApproximately 80 percent of complete moles are homozygous 46XX, resulting from duplication of the haploid genome of a single sperm following fertilization of an ovum in which the maternal chromosomes are lost during meiosis, or as a consequence of postzygotic diploidization of a triploid conception .Approximately 20 percent of complete moles arise by dispermic fertilization of an ovum and may be 46XX or 46XY. However, while complete moles are generally androgenetic because nuclear DNA is paternally derived, mitochondrial DNA is still maternal in origin.Rarely, complete moles are biparental and are associated with an autosomal recessive condition predisposing to molar pregnancy. These patients often have recurrent HMs and may require ovum donation to achieve a livebirth.

PARITAL HYDATIDIFORM MOLEPartial moles are triploid, usually resulting from fertilization of an apparently normal ovum by two sperm or occasionally by a diploid sperm, and may therefore be 69XXX, 69XXY, or 69XYY . Partial moles are the only type of GTD that are associated with the presence of a fetus, and fetal cardiac activity may be detected. Partial mole results in hCG levels that are generally lower than in complete mole, and thus is less likely to be associated with sequelae of hCG stimulation.

EPIDEMIOLOGYThe incidence of HM is difficult to establish with certainty because of the low frequency of the disease and regional variation in reported rates .The reported incidence of HM varies widely in different regions of the world . North American and European countries report low or intermediate rates of HM (66 to 121 per 100,000 pregnancies), whereas Latin American, Asian, and Middle Eastern nations report a wide range, including high rates (23 to 1299 per 100,000 pregnancies)

PRINCIPLES OF PATHOLOGYPathologic Diagnosis of Benign, Noninvasive Hydatidiform Mole:

RISK FACTORSPrior molar pregnancy.Extremes of maternal age – The risk of complete mole is highest at extremes of maternal age (≤15 and >35 years).A history of prior spontaneous abortion and infertility.Dietary factors . Case-control studies have observed that the risk for complete mole progressively increased with decreasing levels of consumption of dietary carotene (vitamin A precursor) and animal fat. OCP and irregular menses are the only known risk factors for partial molar pregnancy.

CLINICAL FEATURESVaginal bleedingPelvic pressure or painUterine size greater than gestational ageHyperemesis gravidarumHyperthyroidismOvarian theca lutein cystsPreeclampsia <20 weeks of gestationAnemiaPassage of hydropic vesicles from the vagina

WORK UP

Pelvic ultrasoundComplete mole Sonographic features suggestive of a complete mole include :Absence of an embryo or fetus. Absence of amniotic fluid.Central heterogeneous mass with numerous discrete anechoic spaces "snowstorm or Swiss cheese pattern" The sonographic appearance of complete mole is variable. There may be a large, central fluid collection that mimics an anembryonic gestation (missed or incomplete abortion) or a central mass of variable echogenicity without anechoic spaces, presumably because the hydropic villi are too small to visualize sonographically.Ovarian theca lutein cysts

Pelvic ultrasoundPartial moleBased upon ultrasound findings, a partial mole is diagnosed as a missed or incomplete abortion in 15 to 60 percent of cases . Sonographic features suggestive of a partial molar pregnancy include.A fetus may be identified, may be viable, and is often growth restricted.Amniotic fluid is present, but the volume may be reduced.Placenta with one or more abnormal findings – Enlarged, cystic spaces ("Swiss cheese pattern") and/or increased echogenicity of chorionic villi.Increased transverse diameter of the gestational sac – These changes in the shape of the gestational sac may be part of the embryopathy of triploidy.Theca lutein cysts are usually absent.

DIAGNOSISThis can be made based upon pelvic ultrasound findings characteristicof complete or partial mole and associated clinical features:Complete mole – If the ultrasound is indeterminate, a clinical diagnosis of complete mole can be made based upon a human chorionic gonadotropin (hCG) >100,000 mIU/mL . Additional supportive findings are theca lutein cysts or hyperthyroidism without another likely etiology. Patients who present with preeclampsia at <20 weeks should be considered to have gestational trophoblastic disease unless proven otherwise.

DIAGNOSISPartial mole – Partial mole is difficult to diagnose on ultrasound. A fetus may be present, but may be growth restricted or have low amniotic fluid. Characteristic sonographic findings are present in a minority of cases. The hCG may be elevated above the expected level, but if it is <100,000 mIU/mL, it is not informative. hCG levels vary in normal pregnancy and there is not a standard level for each gestational age. A uterine curettage may be performed if a fetal heartbeat is not present at an appropriate hCG level and gestational age. For earlier gestations, the patient should be followed with serial ultrasound and hCG levels (eg, weekly) until a normal pregnancy can be ruled out.

CHOICE OF PROCEDURE FOR REMOVAL OF MOLAR TISSUEuterine evacuation hysterectomy:Signs of trophoblastic proliferation (uterine size greater than gestational age, serum human chorionic gonadotropin [hCG] levels >100,000 milli-international units/mL, ovarian theca lutein cysts >6 cm in diameter). Age >40 years.Medication-only methods of uterine evacuation (misoprostol, mifepristone, oxytocin) should not be used,although data are limited.

USE OF PROPHYLACTIC CHEMOTHERAPYWe only consider it in patients who have complete moles, who are being treated by evacuation rather than hysterectomy, who are at high risk of developing GTN (ie, they have signs of trophoblastic proliferation, uterine size greater than gestational age, serum human chorionic gonadotropin [hCG] levels >100,000 milli-international units/mL, and ovarian theca lutein cysts >6 cm in diameter, and are age >40 years), and in whom hCG follow-up is either unavailable or unreliable.

POSTOPERATIVE MONITORING

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