Gestational trophoblastic neoplasms

Composed of complete and partial molar pregnancy, invasive mole, placental site trophoblastic tumor and choriocarcinoma.

Refers to a group of benign and malignant tumors that develop in the uterus from placental tissue.

Malignant forms of gestational trophoblastic disease are collectively referred to as gestational trophoblastic neoplasia and include invasive mole, choriocarcinoma, placental site trophoblastic tumor, and epithelioid trophoblastic tumor.

Hydatidiform mole encompasses about 80% of all gestational trophoblastic disease: invasive moles account for 15%, choriocarcinoma and other rarer types of gestational tumor neoplasia comprise the remaining 5%.

Pathogenesis is unique in that maternal tumors arise from gestational tissue that can have locally invasive or metastatic potential.

Highly curable tumors, even in the presence of extensive metastatic disease.

Typically follows a molar pregnancy, but can occur with any gestational event.

After complete and partial hydatidiform mole, gestational trophoblastic neoplasia develops in 15-20% and 1%-4% of patients, respectively with local uterine Asian with or without metastases.

Gestational trophoblastic neoplasia most commonly follows a molar pregnancy but may develop after any gestation.

Highest incidence is in Asia with a reported rate 3-10 times greater than in Western societies.

In Taiwan rate of molar pregnancy is 1 per 125 pregnancies and the U.S. it is 1 per 1,500 live births.

The incidence of molar pregnancy in the U.S. is about 1 in 1000-2000 pregnancies.

The most common form of GTN is hydatidiform mole, also known as molar pregnancy.

Complete and partial hydatidiform mole differ in their chromosomal pattern, gross morphology, and histopathology.

Complete hydatidiform mole is generally diploid, and the molar chromosomes are generally entirely of paternal origin.

Complete hydatidiform moles have hyper plastic trophoblastic cells and many patients will have marked elevations of hCG, at times greater than 100,000 international units per liter.
Such elevations in hCG are observed in less than 10% of patients with partial hydatidiform mole.

Partial hydatidiform mole is generally tripoid, in which the extra set of chromosomes is of paternal origin.

Partial hydatidiform mole Is diagnosed as an incomplete or missed abortion in 15-60% of cases.
Ultrasound findings suggesting Partial hydatidiform mole include cystic spaces in the placenta, increased diameter of the gestational sack, in the presence of fetal embryonic tissue and amniotic fluid.
Measuring hCG level may help distinguish complete from partial hydatidiform mole from a missed abortion.

And hCG level of greater than 100,000 mIU;mL In the first trimester should strongly raise the suspicion of a molar pregnancy

Rate of complete molar pregnancy increases with decreasing consumption of dietary carotene and animal fat (Berkowitz RS).

It is not known how vitamin A deficiency results in an increased incidence of molar pregnancy.

Women older than 40 years have a 5-10 fold increased risk of developing a complete molar pregnancy.

One in three pregnancies in women over the age of 50 years result in a molar pregnancy and they have a higher risk of developing a gestation trophoblastic tumor.

Hydatiform moles can be partial or complete based on gross, pathological and karyotype findings.

Complete moles usually have 46 XX (90%) or 46 XY (10%) karyotype with all molar chromosomes derived from the father.

Most hydatidiform moles or androgenetic diploids, having to the internal sets of chromosomes and or sporadic.

Diploid biparental moles constitute less than 1% of complete hydatidiform moles, are associated with autosomal recessive process, familial recurrence hydatidiform moles.

Women with familial recurrent moles have recurrent pregnancy loss and less than one chance and 50 of achieving a normal pregnancy.

Most patients with familial recurrent hydatidiform moles have mutations in NLRP7.

No treatment presently exists for recurrent familial hydatidiform moles, and each successive molar pregnancy carries a risk of malignant transformation requiring chemotherapy.

Patients with familial recurrent hydatidiform moles should avoid pregnancy.

A complete mole occurs when an egg is either lost or inactivated and the sperm duplicates itself because the egg was lacking genetic information.

In a complete molar pregnancy no fetus, placenta or amniotic membranes are present.

Characteristically complete hydatidiform mole includes excessive uterine enlargement, theca luteinizing ovarian cystsr, hyperemesis, pre-eclampsia, and hyperthyroidism..

Molar pregnancy associated with molar tissue, resembling grapes, filling the uterus making the uterus larger than it should be for gestational age with fluid filled vesicles.

Postmolar geststational trophoblastic neoplasms includes invasive mole and choriocarcinoma, which developed in about 15-20% of complete moles, but in only one-5% of partial moles.

The incidence of gestational trophoblastic neoplasm after molar pregnancy is 18%-29%.

Invasive moles arise from extension of hydatidiform mole via tissue or venous channels.

Approximately 50% of invasive moles metastasize to the lung or vagina.

Persistent elevated hCG after evacuation of a molar pregnancy most often leads to the diagnosis of invasive mole.

Choriocarcinoma develops from villous trophoblast.

Choriocarcinoma occurs with different types of pregnancy events including hydatidiform mole, 50% of the time, term orvpreterm gestation, 25%, and tubal pregnancy or abortion 25%.

Approximately 2-3% of hydatidiform moles progress choriocarcinoma.

Subsequent pregnancies ate usually normal.

In the absence of a placenta bleeding molar pregnancy is associated with bleeding into the uterus cavity or vaginal bleeding.

Partial moles are a result of two sperm fertilizing the same egg and it may be associated with partial placentas, membranes and even a fetus with genetic problems.

A partial mole may exist with twin pregnancy but only one twin usually survives.

Ultrasound is the most precise method of diagnosing complete hydatidiform mole and partial hydatidiform before evacuation.

Ultrasound findings include a heterogeneous uterine mass with cystic spaces, no identifiable fetus or embryo, and no amniotic fluid.

Classic ultrasound findings may be subtle or absent in the early first trimester of complete high hydatidiform mole.

Estimates of the sensitivity of pelvic ultrasound in diagnosing complete mole range from 70-80%, and increases with gestational age.

Partial hydatidiform mole is more frequently misdiagnosed as an incomplete or missed abortion compared with complete hydatidiform mole, because partial hydatidiform mole is associated with fetal or embryonic tissue and amniotic fluid.

In a phase 3 trial of 216 eligible women with low risk gestational trophoblast neoplasms dactinomycin 1.25 mg per meter squared biweekly intravenously compared to intramuscular methotrexate 30 mg for meter squared resulted in a complete remission rate of 70% versus 53%, respectively (Osborne RJ et al).

In a study of 76 women with persistently raised, but falling serum human chorionic gonadotropin concentrations 6 months after evacuation was associated with a return to normal in most patients under surveillance: only a small number of patients will require therapy in this scenario and suggests falling hCG values represent spontaneous, although slow progression of residual molar tissue (Agarwal R et al).

Initial treatment of hydatidiform mole for women who wish to preserve fertility is suction dilatation and curettage, performed under ultrasound guidance to reduce the risk of uterine perforation.
Rho(D) immunoglobulin is it listed at the time of the evacuation to patients with Rh negative blood types.
For women who do not wish to preserve fertility or who are older hysterectomy is considered as an alternative for hydatidiform mole,
Prophylactic chemotherapy at the time of uterine evacuation may reduce the incidence of post molar gestational trophoblastic neoplasm by 3-8%: prophylactic methotrexate or dactinomycin can be considered for patients at high risk for post molar gestational trophoblastic neoplasm.
Risk of post molar gestational trophoblastic neoplasm includes age greater than 40 years, hCG levels in excess of 100,000 mIU per mL and excessive uterine enlargement and or theca lutein cysts larger than 6 cm.

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