Hydatidiform Mole

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2021-01-23

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KHDC3L, NLRP7, CORO1A, H3P47, MEI1, CDKN1C, CIB2, TP53, BCL2, ERBB2, SPP1, PTEN, NLRP2, EGFR, LEP, HYMAI, LGALS1, VEGFA, HLA-DOA, MMP2, CNMD, PLAGL1, TP63, UVRAG, TNFSF14, TP53BP2, ZBTB16, PSCA, TIMP3, TK1, TH, TERT, TERC, TEP1, STAT3, SOX2, RRM2, RPE65, SRGAP3, PDCD4, PPP1R13L, CGB8, PSG10P, POU5F1P4, POU5F1P3, MIR196B, PSG8, MIR21, PADI6, ZACN, CGB2, CGB1, CGB5, CKAP4, NANOG, HPSE2, GKN1, AKIRIN2, ZBTB7A, ERVW-1, CD274, PSG6, SRGAP2, PPP1R13B, PSMB9, ABO, PSG5, HOXC@, HLA-A, HIC1, GH1, FTL, ERV3-1, EGF, EDN1, VCAN, CSF2, CSF1R, CSF1, CHM, CHGB, CGB3, CDKN2A, CDKN1B, CDKN1A, CDH11, CCT, CASP10, BDNF, ASCL2, APOB, AKT1, NR0B1, HLA-DRB1, HOXC4, HTRA1, HOXC5, PPARG, POU5F1, ADA, PAK1, PAEP, NME1, MSH2, MRC1, MLH1, MAP3K1, MEFV, MCL1, KRT31, ITGB1, INHA, IGH, IGFBP1, IGF2, IGF1, HSPA5, HOXC13, HOXC12, HOXC9, HOXC8, HOXC6, H3P10

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A hydatidiform mole is a benign gestational trophoblastic disease developing during pregnancy. Resulting from an abnormal fertilization characterized by trophoblastic proliferation, normal embryo development is rendered impossible. Hydatidiform moles can be either complete or partial.

Epidemiology

The condition appears to occur in approximately 1/1,000 pregnancies and in 1/41 miscarriages in Europe.

Clinical description

Complete moles are asymptomatic in 40% of cases. Most often, a mole is detected upon suspicion of miscarriage in the first trimester, with bleeding and pelvic pain. The clinical signs in the second trimester (vomiting, metrorrhagia, abnormal increase in the size of the uterus, and more rarely anemia or preeclampsia) are observed less often, due to early detection by ultrasound examination. Hyperthyroidism is exceptional. The clinical signs of a partial mole (metrorrhagia, vomiting, etc.) are rare. A mole is usually detected histologically on analysis of aspiration samples from a suspected miscarriage.

Etiology

The moles are caused by abnormal fertilization with an excess of paternal chromosome material. Complete moles result from fertilization of an enucleated ovocyte by one or two haploid spermatozoa. The caryotype is 46,XX (75% of cases) or 46,XY (25%). The mole is characterized by trophoblastic hyperplasia associated with generalized degeneration of chorionic villi and absence of an amniotic cavity and embryonal tissue. Partial moles result from fertilization of a normal ovocyte by two spermatozoa or one abnormal spermatozoon. This type of mole is characterized by focal trophoblastic hyperplasia, localized degeneration of chorionic villi and identifiable embryonal tissue. The caryotype is triploid in 99% of cases.

Diagnostic methods

Ultrasound of a complete mole may show a classic ''snow storm'' appearance (solid, hyperechoic areas of varying forms interspersed with liquid areas of various sizes) occupying the entire uterine cavity. Earlier ultrasound before 9-10 weeks of pregnancy shows a limited vesicular appearance of the placenta. Ultrasound of a partial mole shows focal vesicular damage. Embryonic structures without an increase in uterine size are commonly found. Diagnosis is based on histological examination of the product of fertilization. Double reading by a pathology expert is often useful. When hydatidiform mole is suspected, determination of total chorionic gonadotropin (hCG) must be performed.

Differential diagnosis

Moles must not be confused with gestational trophoblastic neoplasms (see this term) nor with prolonged retention of a ''classic'' spontaneous miscarriage.

Genetic counseling

Aside from very rare cases of recurrent moles in the same patient or in the same family (< 1% of cases, in which a mutation in the NLRP7 or KHDC3L genes have sometimes been found), genetic counseling is not required.

Management and treatment

Treatment of moles consists of ultrasound-guided suction evacuation. Evacuation must be scheduled rapidly due to the risk of complications, which increases with gestational age.

Prognosis

After removal, the prognosis is excellent. The main risk is retention by incomplete aspiration (25% of cases) justifying ultrasound follow-up within 15 days of aspiration. Retention (ultrasound image of more than 17 mm in anteroposterior diameter) warrants a repeated aspiration. In about 15 % of cases of complete moles and in 0.5 to 5% of partial moles, the condition leads to gestational trophoblastic neoplasm (see this term) complications in the weeks and months following mole evacuation. Monitoring of plasma hCG levels allows diagnosis of possible occurrence of gestational trophoblastic neoplasm which would warrant disease staging and appropriate chemotherapy.