First-trimester molecular diagnosis of complete hydatidiform mole associated with dizygotic twin pregnancy conceived by intrauterine insemination

Twin/Multiple Gestations With a Hydatidiform Mole: Clinicopathologic Analysis of 21 Cases With Emphasis on Molecular Genotyping and Parental Contribution

Complete hydatidiform moles (CHMs) and partial hydatidiform moles (PHMs) are abnormal gestations characterized by vesicular chorionic villi accompanied by variable trophoblastic hyperplasia, with or without embryonic development. CHMs are purely androgenetic (only paternal [P] chromosome complements), mostly homozygous/monospermic (~85%) but occasionally heterozygous/dispermic, whereas PHMs are overwhelmingly diandric triploid (2 paternal [P] and 1 maternal [M] chromosome complements) and heterozygous/dispermic (>95%). The presence of a fetus in a molar pregnancy usually indicates a PHM rather than a CHM; however, CHMs and PHMs rarely can be associated with a viable fetus or a nonmolar abortus in twin pregnancies and rare multiple gestation molar pregnancies have been reported. A "one-oocyte-model," with diploidization of dispermic triploid zygotes, has been proposed for twin CHM with coexisting fetus, and a "two-oocyte-model" has been proposed for twin PHM with coexisting fetus. Among 2447 products of conception specimens, we identified 21 cases of twin/multiple gestations with a molar component, including 20 CHMs (17 twins, 2 triplets, 1 quintuplet) and 1 PHM (twin). P57 immunohistochemistry was performed on all; DNA genotyping of molar and nonmolar components was performed on 9 twin CHMs, 1 triplet CHM, 1 quintuplet CHM, and 1 twin PHM. All CHM components were p57-negative and those genotyped were purely androgenetic. Twin CHMs had genotypes of P1M1+P2P2 in 5, P1M1+P1P1 in 1, and P1M1+P2P3 in 1, consistent with involvement of 1 oocyte and from 1 to 3 sperm-most commonly a homozygous CHM but involving 2 sperm in the whole conception-and compatible with a "one-oocyte-model." The triplet CHM was P1M1+P1P1+P2M2 and the quintuplet CHM was P1M1+P2M2+P2M2+P3M3+P4P4, consistent with involvement of 2 sperm and at least 2 oocytes for the triplet and 4 sperm and at least 3 oocytes for the quintuplet. The twin PHM had a P1M1+P2P3M2 genotype, consistent with involvement of 2 oocytes and 3 sperm. p57 immunohistochemistry is highly reliable for diagnosis of CHMs in twin/multiple gestations. Refined diagnosis of molar twin/multiple gestations is best accomplished by correlating morphology, p57 immunohistochemistry, and molecular genotyping, with the latter clarifying zygosity/parental chromosome complement contributions to these conceptions.

Obstetrical and oncological outcomes of twin pregnancies with hydatidiform mole and coexisting fetus

OBJECTIVE

To evaluate the obstetrical and oncological progression of twin pregnancies with hydatidiform mole coexisting fetus (HMCF).

MATERIALS AND METHODS

Using a retrospective method based on patients from the Women's Hospital, Zhejiang University School of Medicine database between January 1990 and October 2020, 17 patients were histologically confirmed as having HMCF, and the patients' prenatal diagnosis, outcomes and development of gestational trophoblastic neoplasia (GTN) were reviewed.

RESULTS

Among these 17 cases, 11 (64.71%) cases were complete hydatidiform mole coexisting fetus (CHMCF), and 6 (35.29%) cases were partial hydatidiform mole coexisting fetus (PHMCF). The gestational age at diagnosis of CHMCF was significantly earlier than that of PHMCF [9 (8-24) vs. 18 (11-32) weeks, respectively, P < 0.05]. The live birth rate of PHMCF was slightly higher than that of CHMCF (33.33%; 18.18%), but this difference was not statistically significant. The overall rate of GTN incidence of HMCF was 47.06% (8/17), and the GTN rates of PHMCF and CHMCF were 33.33% (2/6) and 54.55% (6/11), respectively. There was no significant difference in the GTN rate between patients who chose to continue pregnancy and those who terminated pregnancy before 24 weeks of gestation. The GTN rate of patients with term delivery was not significantly higher than that of preterm delivery.

CONCLUSION

In HMCF cases, the incidence rate of CHMCF was higher than that of PHMCF, and PHMCF is more difficult to diagnose in the early stage. Continuing pregnancy does not increase the risk of GTN compared to terminating pregnancy. In cases of HMCF, when the fetal karyotype is normal and maternal complications are controlled, it is safe to continue the pregnancy and extend it to term.

Molecular and Immunohistochemical Characteristics of Complete Hydatidiform Moles

Molar pregnancy is a gestational trophoblastic disease that belongs to the category of precancerous lesions. On the other end of the spectrum are gestational trophoblastic neoplasms such as invasive mole, choriocarcinoma, placental site trophoblastic tumor and epithelioid trophoblastic tumor, which are considered malignant tumors. Based on defined histopathological criteria, molar pregnancy is divided into partial and complete hydatidiform mole. Especially in the case of early complete mole, the diagnosis can be quite challenging and often necessitates additional molecular or immunohistochemical methods. The aim of this study was to assess the importance of additional molecular and immunohistochemical methods to accurately diagnose complete hydatidiform mole and to stress the importance of correct diagnosis and close follow-up of these patients. A total of 367 consecutive cases of spontaneous abortion were analyzed in a 3-year period. Eight cases with histopathological diagnosis of complete molar pregnancy were selected for further analysis. Apart from standard microscopic analysis, additional molecular and immunohistochemical analyses were performed in all eight cases. Most of the histopathological characteristics of complete molar pregnancy were present in all cases, together with complete absence of positivity for the p57 immunohistochemical marker in the cytotrophoblasts and villous stromal cells. The molecular analysis revealed androgenetic diploidy in seven cases and biparental diploidy in one case with more than three consecutive complete molar pregnancies. Additional immunohistochemical and molecular methods can considerably aid in the correct diagnosis of molar pregnancy.