Placental mesenchymal dysplasia initially diagnosed as partial mole

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.

A Challenging Diagnosis: Placental Mesenchymal Dysplasia—Literature Review and Case Report

We describe a 22-year-old woman (2-gravid) case who was referred to our clinic at 18 weeks of gestation for a placenta with vesicular lesions discovered on prenatal examination routine. An ultrasound exam at 31 weeks of gestation showed numerous vesicular lesions, which gradually augmented as the pregnancy advanced. A live normal-appearing fetus was confirmed by intrauterine growth restriction (IUGR). The maternal serum β-human chorionic gonadotropin level remained in normal ranges. At some point, a multidisciplinary medical consensus considered the termination of the pregnancy, but the patient refused to comply. At 33 weeks of gestation, preterm premature rupture of membranes (pPROM) occurred, and she spontaneously delivered a 1600 g healthy female baby with a good long-term outcome. Placental mesenchymal dysplasia (PMD) was retrospectively diagnosed after confronting the data from ultrasound, chorionic villus sampling (CVS), amniocentesis, pathological examination, and immunohistochemical stain. The lack of sufficient reports of PMD determines doctors to be cautious and reserved, approaching these cases more radically than necessary. We reviewed this disease and searched for all cases of PMD associated with healthy, live newborns.

Loss of p57 Expression in Conceptions Other Than Complete Hydatidiform Mole: A Case Series With Emphasis on the Etiology, Genetics, and Clinical Significance

Combined p57 immunohistochemistry and DNA genotyping refines classification of products of conception specimens into specific types of hydatidiform moles and various nonmolar entities that can simulate them. p57 expression is highly correlated with genotyping and in practice can reliably be used to identify virtually all complete hydatidiform moles (CHM), but aberrant retained or lost p57 expression in rare CHMs and partial hydatidiform moles (PHM), as well as loss in some nonmolar abortuses, has been reported. Among a series of 2329 products of conceptions, we identified 10 cases for which loss of p57 expression was inconsistent with genotyping results (none purely androgenetic). They displayed a spectrum of generally mild abnormal villous morphology but lacked better developed features of CHMs/early CHMs, although some did suggest subtle forms of the latter. For 5 cases, genotyping (4 cases) and/or ancillary testing (1 case) determined a mechanism for the aberrant p57 results. These included 3 PHMs-2 diandric triploid and 1 triandric tetraploid-and 1 nonmolar specimen with loss of p57 expression attributable to partial or complete loss of the maternal copy of chromosome 11 and 1 nonmolar specimen with Beckwith-Wiedemann syndrome. For 5 cases, including 2 diandric triploid PHMs and 3 biparental nonmolar specimens, genotyping did not identify a mechanism, likely due to other genetic alterations which are below the resolution of or not targeted by genotyping. While overdiagnosis of a PHM as a CHM may cause less harm since appropriate follow-up with serum β-human chorionic gonadotropin levels would take place for both diagnoses, this could cause longer than necessary follow-up due to the expectation of a much greater risk of persistent gestational trophoblastic disease for CHM compared with PHM, which would be unfounded for the correct diagnosis of PHM. Overdiagnosis of a nonmolar abortus with loss of p57 expression as a CHM would lead to unnecessary follow-up and restriction on pregnancy attempts for patients with infertility. Genotyping is valuable for addressing discordance between p57 expression and morphology but cannot elucidate certain mechanisms of lost p57 expression. Future studies are warranted to determine whether chromosomal losses or gains, particularly involving imprinted genes such as p57, might play a role in modifying the risk of persistent gestational trophoblastic disease for PHMs and nonmolar conceptions that are not purely androgenetic but have some abnormal paternal imprinting of the type seen in CHMs.

Sudden fetal death with placental mesenchymal dysplasia complicated by placenta previa

Placental mesenchymal dysplasia (PMD) is a rare placental abnormality that is closely related to severe pregnancy complications. A 27-year-old woman with fetal growth restriction and placenta previa was referred to a university hospital at 22 gestational weeks (GW). She was suspected of having a twin pregnancy with a complete or partial hydatidiform mole and coexisting normal live fetus, because two separate placentas, an enlarged one with multiple cystic lesions and a normal one, were shown on ultrasound examinations. At 27 GW, she experienced a sudden intrauterine fetal death (IUFD) after bleeding due to placenta previa, despite confirmation of fetal well-being at 2 h before bleeding. After delivery, histopathological examination confirmed the diagnosis of PMD. This is the first documented case of a woman with PMD and placenta previa who had a sudden IUFD after bleeding. Patients with both PMD and placenta previa should be considered at extremely high risk for IUFD.

Placental mesenchymal dysplasia: What every radiologist needs to know

Placental mesenchymal dysplasia (PMD) is an uncommon vascular anomaly of the placenta characterized by placentomegaly with multicystic placental lesion on ultrasonography and mesenchymal stem villous hyperplasia on histopathology. Placental mesenchymal dysplasia should be considered in the differential diagnosis of cases of multicystic placental lesion such as molar pregnancy, chorioangioma, subchorionic hematoma, and spontaneous abortion with hydropic placental changes. However, lack of high-velocity signals inside the lesion and a normal karyotype favor a diagnosis of PMD. PMD must be differentiated from gestational trophoblastic disease because management and outcomes differ. We report the case of an 18-year-old female at 15 weeks of gestation with sonographic findings suggestive of placental mesenchymal dysplasia. The diagnosis was confirmed on histopathology.

Variants in Maternal Effect Genes and Relaxed Imprinting Control in a Special Placental Mesenchymal Dysplasia Case with Mild Trophoblast Hyperplasia

Placental mesenchymal dysplasia (PMD) and partial hydatidiform mole (PHM) placentas share similar characteristics, such as placental overgrowth and grape-like placental tissues. Distinguishing PMD from PHM is critical because the former can result in normal birth, while the latter diagnosis will lead to artificial abortion. Aneuploidy and altered dosage of imprinted gene expression are implicated in the pathogenesis of PHM and also some of the PMD cases. Diandric triploidy is the main cause of PHM, whereas mosaic diploid androgenetic cells in the placental tissue have been associated with the formation of PMD. Here, we report a very special PMD case also presenting with trophoblast hyperplasia phenotype, which is a hallmark of PHM. This PMD placenta has a normal biparental diploid karyotype and is functionally sufficient to support normal fetal growth. We took advantage of this unique case to further dissected the potential common etiology between these two diseases. We show that the differentially methylated region (DMR) at NESP55, a secondary DMR residing in the GNAS locus, is significantly hypermethylated in the PMD placenta. Furthermore, we found heterozygous mutations in NLRP2 and homozygous variants in NLRP7 in the mother’s genome. NLRP2 and NLRP7 are known maternal effect genes, and their mutation in pregnant females affects fetal development. The variants/mutations in both genes have been associated with imprinting defects in mole formation and potentially contributed to the mild abnormal imprinting observed in this case. Finally, we identified heterozygous mutations in the X-linked ATRX gene, a known maternal–zygotic imprinting regulator in the patient. Overall, our study demonstrates that PMD and PHM may share overlapping etiologies with the defective/relaxed dosage control of imprinted genes, representing two extreme ends of a spectrum.

Multimodality imaging of placental masses: a pictorial review

Placental masses are uncommonly identified at the time of obstetric ultrasound evaluation. Understanding the pathologies presenting as placental masses is key for providing a differential diagnosis and guiding subsequent management, which may include additional imaging with magnetic resonance (MR) imaging. Potential benign entities include chorioangiomas and teratomas. Larger chorioangiomas can cause fetal cardiovascular issues from volume overload. Placental mesenchymal dysplasia has an association with fetal anomalies and detailed fetal evaluation should be performed when it is suspected. Identifying other cystic masses such as partial and complete moles is crucial to prevent erroneous pregnancy termination. This review addresses normal imaging appearance of the placenta on ultrasound and MR imaging and describes various trophoblastic and nontrophoblastic placental masses. Potential placental mass mimics including uterine contractions and thrombo-hematomas are also presented.

Comprehensive genotype-phenotype correlations between NLRP7 mutations and the balance between embryonic tissue differentiation and trophoblastic proliferation

BACKGROUND

Hydatidiform mole (HM) is a human pregnancy with excessive trophoblastic proliferation and abnormal embryonic development that may be sporadic or recurrent. In the sporadic form, the HM phenotype is driven by an abnormal ratio of paternal to maternal genomes, whereas in the recurrent form, the HM phenotype is caused by maternal-recessive mutations, mostly in NLRP7, despite the diploid biparental origin of the HM tissues. In this study, we characterised the expression of the imprinted, maternally expressed gene, CDKN1C (p57(KIP2)), the genotype, and the histopathology of 36 products of conception (POC) from patients with two defective alleles in NLRP7 and looked for potential correlations between the nature of the mutations in the patients and the various HM features.

METHODS/RESULTS

We found that all the 36 POCs are diploid biparental and have the same parental contribution to their genomes. However, some of them expressed variable levels of p57(KIP2) and this expression was strongly associated with the presence of embryonic tissues of inner cell mass origin and mild trophoblastic proliferation, which are features of triploid partial HMs, and were associated with missense mutations. Negative p57(KIP2) expression was associated with the absence of embryonic tissues and excessive trophoblastic proliferation, which are features of androgenetic complete HMs and were associated with protein-truncating mutations.

CONCLUSIONS

Our data suggest that NLRP7, depending on the severity of its mutations, regulates the imprinted expression of p57(KIP2) and consequently the balance between tissue differentiation and proliferation during early human development. This role is novel and could not have been revealed by any other approach on somatic cells.

Placental mesenchymal dysplasia: case report with gross and histological findings

Placental mesenchymal dysplasia (PMD) is a rare placental disorder characterized by placental enlargement and areas of abnormal, enlarged, grape-like villi. This condition may resemble a partial hydatidiform mole and may occur associated with Beckwith-Wiedemann syndrome (BWS) or in phenotypically normal fetuses. There were 110 cases reported so far. We describe one case with typical gross and microscopic placental lesions.

Placental Mesenchymal Dysplasia

Placental mesenchymal dysplasia is a rare, incompletely understood placental stromal lesion, characterized by placentomegaly and striking ectasia and tortuosity of chorionic plate and stem villous vessels. Its prenatal ultrasonographic and gross pathologic features resemble those of a partial mole, but the fetus is typically normal and the placenta has a diploid, chromosomal complement. We discuss the pathologic features and current understanding of the etiopathogenesis of this condition, the supportive immunohistochemical and confirmatory molecular genetic studies important in its diagnosis, and its implications for pregnancy and infant outcomes.

Diagnostic utility of microsatellite genotyping for molar pregnancy testing

CONTEXT

Molecular genotyping by analysis of DNA microsatellites, also known as short tandem repeats (STRs), is an established method for diagnosing and classifying hydatidiform mole. Distinction of both complete hydatidiform mole and partial hydatidiform mole from nonmolar specimens is relevant for clinical management owing to differences in risk for persistent gestational trophoblastic disease.

OBJECTIVE

To determine the technical performance of microsatellite genotyping by using a commercially available multiplex assay, and to describe the application of additional methods to confirm other genetic abnormalities detected by the genotyping assay.

DESIGN

Microsatellite genotyping data on 102 cases referred for molar pregnancy testing are presented. A separate panel of mini STR markers, flow cytometry, fluorescence in situ hybridization, and p57 immunohistochemistry were used to characterize cases with other incidental genetic abnormalities.

RESULTS

Forty-eight cases were classified as hydatidiform mole (31, complete hydatidiform mole; 17, partial hydatidiform mole). Genotyping also revealed 11 cases of suspected trisomy and 1 case of androgenetic/biparental mosaicism. Trisomy for selected chromosomes (13, 16, 18, and 21) was confirmed in all cases by using a panel of mini STR markers.

CONCLUSIONS

This series illustrates the utility of microsatellite genotyping as a stand-alone method for accurate classification of hydatidiform mole. Other genetic abnormalities may be detected by genotyping; confirmation of the suspected abnormality requires additional testing.

Placentomegaly and placental mesenchymal dysplasia

A 23-year-old primigravida presented to the labour ward at 37 weeks gestation referred with intrauterine growth restriction, oligohydramnios and placentomegaly. Differential diagnoses of placentomegaly were considered. Her antenatal blood screening tests were normal. There were no fetal malformations. However, triple screen and fetal karyotype were not done as patient presented late in pregnancy. The patient soon went into spontaneous labour and delivered a girl weighing 2.15 kg with a normal Apgar score. The cord was long and twisted; placenta was bulky, 1.7 kg, with prominent grape-like vesicles involving whole placenta with a rim of normal placenta at the periphery. Microscopy showed some areas of multiple villi with marked hydropic changes and myxoid degeneration, preserved vasculature and no trophoblastic proliferation. Placental mesenchymal dysplasia was thus diagnosed. The baby had no evidence of Beckwith-Wiedemann syndrome. The child is now 3 years old with normal development and is doing well.

Placental mesenchymal dysplasia: a case report

Introduction. A rare case of histologically proven placental mesenchymal dysplasia (PMD) with fetal omphalocele in a 22-year-old patient is reported. Material and Methods. Antenatal ultrasound of this patient showed hydropic placenta with a live fetus of 17 weeks period of gestation associated with omphalocele. Cordocentesis detected the diploid karyotype of the fetus. Patient, when prognosticated, choose to terminate the pregnancy in view of high incidence of fetal and placental anomalies. Subsequent histopathological examination of placenta established the diagnosis to be placental mesenchymal dysplasia. Conclusion. On clinical and ultrasonic grounds, suspicion of P.M.D. arises when hydropic placenta with a live fetus presents in second trimester of pregnancy. Cordocentesis can detect the diploid karyotype of the fetus in such cases. As this condition is prognostically better than triploid partial mole, continuation of pregnancy can sometimes be considered after through antenatal screening and patient counseling. However, a definite diagnosis of P.M.D. is made only on placental histology by absence of trophoblast hyperplasia and trophoblastic inclusions.

Placental mesenchymal dysplasia

Placental mesenchymal dysplasia is a benign condition that can be confused with a molar pregnancy by ultrasound scanning and gross examination. Conservative management should be considered with a normal-appearing singleton fetus and a cystic-appearing placenta. We present a case of placental mesenchymal dysplasia with a favorable outcome.

Partial molar pregnancy with a chromosomically and phenotypically normal embryo: presentation of an extremely rare case and review of literature

We present an extremely rare case of partial molar pregnancy with a chromosomically and phenotypically normal embryo and review of the literature. A 31-year-old nulliparous was referred to us at 30 weeks of gestation due to absence of fetal movements and subsequent ultrasound examination revealed intrauterine demise. Prenatal amniocentesis due to raised maternal serum α-fetoprotein had shown a karyotypically normal female embryo and second trimester ultrasound demonstrated no anatomic abnormalities. Upon induction of labor with misoprostol, a phenotypically normal embryo was delivered and the placenta showed intermixed areas of marked hydatidiform villous change and normal parenchyma. Pathologic examination of the placenta confirmed the molar change of placenta. Two are the main theories discussed herein that explain the placental molar changes in singleton pregnancies: confined placental mosaicism (one case reported to date) and placental mesenchymal dysplasia (70 cases reported). Differential diagnosis is based on histopathologic features and genetic analysis of placenta.

Placental mesenchymal dysplasia associated with hepatic and pulmonary hamartoma

This report describes a 31-week stillborn female infant with placental mesenchymal dysplasia (PMD) in association with hepatic mesenchymal hamartoma (HMH) and pulmonary hamartoma. Placental mesenchymal dysplasia was initially misdiagnosed as a partial mole. However, histologically, no trophoblastic proliferation or inclusions were observed. Differential diagnosis of the hepatic mass with similar tumors is discussed. To our knowledge, this is the first case of lung hamartoma reported in a fetus and the first case related to PMD and HMH. A common anomalous development of the mesoderm, a reparative post-injury process and a genetic mechanism, have been proposed to explain their pathogenesis.

Three-dimensional sonography of placental mesenchymal dysplasia and its differential diagnosis

OBJECTIVE

Placental mesenchymal dysplasia (PMD) is an uncommon vascular anomaly of the placenta characterized by mesenchymal stem villous hyperplasia. Its main sonographic feature is a thickened placenta with hypoechoic areas, and an accurate sonographic diagnosis is challenging. The aim of this study was to report 2 cases of PMD and discuss the differential diagnosis of its sonographic features.

METHODS

Cases of placental masses were studied by 2-dimensional (2D), 3-dimensional (3D), and color Doppler imaging.

RESULTS

In case 1, a thick placenta with multiple hypoechoic areas was noted at 13 weeks' gestation. At 19 weeks, the multicystic area, clearly demarcated from a normal-looking placenta, measured 6.5 x 8.5 cm and enlarged gradually. The patient gave birth to a 625-g female neonate after spontaneous labor at almost 26 weeks' gestation. In case 2, a first sonographic examination at 25 weeks' gestation revealed a thickened placenta with hypoechoic areas and a fetus with a single umbilical artery and a ventricular septal defect. At 27 weeks, the abnormal area of the placenta measured 14.5 x 7.5 cm. At 32 weeks' gestation, a caesarean delivery was performed because of a nonreassuring fetal heart tracing, and a 1415-g female neonate was delivered. Both cases were evaluated by 2D, 3D, and color Doppler imaging, and the pathologic features of both placentas were consistent with PMD.

CONCLUSIONS

Placental mesenchymal dysplasia should be considered in the differential diagnosis of every placental mass, especially in cases of multicystic placental lesion with lack of high-velocity signals inside the lesion, and a normal karyotype.

Immunohistochemical expression of p57 in placental vascular proliferative disorders of preterm and term placentas

P57 protein is implicated in some human imprinting disorders such as hydatiform mole and Beckwith-Wiedemann syndrome (BWS), both characterized by mesenchymal and vascular placental abnormalities. We investigated p57 immunohistochemical expression in placental vascular proliferative disorders of preterm and term placentas, including chorangiosis (n = 5), chorangiomatosis (n = 2), chorangiomas (n = 7), umbilical cord angioma (n = 1), and placental mesenchymal dysplasia (PMD) (n = 7). P57 was expressed in decidua, cytotrophoblast, intermediate trophoblast and stromal cells of normal terminal, intermediate and stem villi, umbilical cord, chorangiosis, chorangiomatosis, and chorangiomas. In contrast, there was a loss of p57 expression in stromal cells of dysplastic stem villi in all cases of PMD regardless of whether associated with BWS or not. P57 seems to be involved in the pathogenesis of a subset of placental vascular proliferative disorders in preterm and term placentas, such as PMD. The loss of p57 expression in PMD could be of diagnostic value in helping to distinguish this rare placental lesion from its mimickers.

Placental mesenchymal dysplasia associated with trisomy 13: sonographic findings

Placental mesenchymal dysplasia (PMD) is a rare placental abnormality with sonographic and macroscopic features similar to those seen in a partial hydatidiform mole, and which has usually been reported with a normal female karyotype. We report a case of prenatally suspected PMD associated with trisomy 13. Sonography performed at 17 weeks' gestation showed multiple cystic spaces in the placenta resembling molar tissue, and a fetus with postaxial polydactyly and an atrial septal defect. An amniocentesis revealed a fetal karyotype of 46,XY,der(13), t(13;13)(q11;q11)[20]/47,XY,+13[11], consistent with trisomy 13. Cordocentesis confirmed the cytogenetic diagnosis. Histopathologic examination of the placenta following termination of the pregnancy at 22 weeks' gestation showed enlarged stem villi with loose connective tissue and cistern formation and no evidence of trophoblastic hyperplasia or stromal trophoblastic inclusions, which was consistent with PMD. PMD should be considered in the differential diagnoses of a placenta showing multiple cystic lesions on prenatal sonography, and karyotypic analysis should be performed.

Placental pathology, a survival guide

Placental pathology continues to be an underutilized, undertaught, and inadequately handled surgical subspecialty. The requests for placental pathology are soaring, due partly to demands from obstetricians and to the litigious environment in which they practice, and to improved obstetrical care leading to pregnancies in medically challenging situations. Evaluation of the placenta requires a good understanding of the questions and issues concerning both the fetus/infant and the mother. Information from placental pathology can be critical in early neonatal care and in reproductive planning for the family, and it can provide risk assessment for neurologic outcome of the infant. A comfortable interaction among the obstetric staff, mothers, and pathologists often obviates need for legal intervention in unexpected pregnancy outcomes. Some critical pathologic features that involve maternal and fetal management are illustrated herein. A template for gross examination and a few critical histopathologic diagnostic features with clincopathologic correlation are included.

Placental mesenchymal dysplasia associated with fetal overgrowth and mosaic deletion of the maternal copy of 11p15.5

Placentae with mesenchymal dysplasia (PMD) are typically larger than average and show cystic areas on ultrasonography. Fetal outcomes are variable and are often associated with growth restriction. However, enigmatically, some associated fetuses show signs of Beckwith-Wiedemann syndrome (BWS). PMD has recently been shown to result from androgenetic (complete paternal uniparental disomy) chimerism in the placenta in pregnancies that were associated with some fetal growth restriction. Cases of PMD associated with overgrowth have not previously been investigated molecularly. We present a case of focal PMD associated with a male fetus showing overgrowth with an enlarged heart, marked fetal ascites and intrauterine fetal death at 34 weeks, but no other BWS manifestations. Mosaicism for an unbalanced translocation leading to deletion of the maternal copy of the BWS region on 11p15.5 and partial duplication of 17q was observed in placenta, but not fetal samples. While the placental findings of PMD can be caused by an unbalanced dosage of genes in 11p15.5 alone, fetal growth parameters appear to depend on the underlying mechanism and likely also the level and distribution of abnormal cells.

P57kip2 immunohistochemical expression and ultrastructural findings of gestational trophoblastic disease and related disorders

Gestational trophoblastic disease (GTD) is a unique spectrum of diseases ranging from complete hydatidiform mole (CHM), partial hydatidiform mole (PHM), and invasive mole (IM) to choriocarcinoma (CC). Placental site trophoblastic tumor (PSTT) and epithelioid trophoblastic tumor (ETT) have been classified as related disorders. Mesenchymal dysplasia (MD) may be misdiagnosed as PHM; however, it is said to have a quite different histogenesis from PHM. P57kip2 is the protein product of a paternally imprinted or maternal gene that inhibits cyclin-dependent kinases (CDK), thus serving to inhibit cell proliferation and to suppress tumor growth. Its lack of expression in trophoblastic disease plays a role in its abnormal proliferation and differentiation. In this study, P57kip2 immunostaining was absent in the trophoblastic layers of CHM and was positive in the trophoblast layer of nonmolar villi and MD. Ultrastructure of complete molar cystic villi showed tree-like branching of microvillous processes and intracytoplasmic lacunae without capillaries in the stroma, whereas MD contained many newly formed blood vessels and collagen. Also, large lacunae with microvilli and polymorphic nuclei of syncytiotrophoblast cells with well-developed organelles were observed in IM. Lung ETT following CHM and normal deliveries showed two types of large mononuclear cells and binuclear cells with abundant organelles and bundles of intermediate-type filaments in the stroma.

Placental mesenchymal dysplasia

CONTEXT

Placental mesenchymal dysplasia is characterized by placentomegaly and may be mistaken for molar pregnancy both clinically and macroscopically because of the presence of "grapelike vesicles." It may be associated with a completely normal fetus, a fetus with growth restriction, or a fetus with features of Beckwith-Wiedemann syndrome.

OBJECTIVE

To review the etiology, molecular pathology, gross and microscopic features, clinical presentation, complications, and differential diagnosis of placental mesenchymal dysplasia.

DATA SOURCES

The PubMed and the Medline databases were systematically searched for articles between 1970 and 2006. The following keywords were used: placental mesenchymal dysplasia, mesenchymal hyperplasia, molar pregnancy, pseudomolar pregnancy, Beckwith-Wiedemann syndrome, and placentomegaly. Relevant references from review articles were also searched.

CONCLUSIONS

Placental mesenchymal dysplasia should be considered in the differential diagnosis when the ultrasonographic findings show a cystic placenta. Close attention should be paid to fetal morphology for early recognition of fetal complications and to prevent unnecessary termination of pregnancy in cases associated with a normal fetus.

Placental mesenchymal dysplasia associated with hepatic mesenchymal hamartoma in the newborn

Placental mesenchymal dysplasia is an uncommon disorder in which the placenta is enlarged with abnormal, large, and often cystic villi with dilated and/or thick-walled vessels. These placental changes can mimic a partial hydatidiform mole but in contrast to a partial mole can coexist with a fully viable fetus. Fetal anatomical and vascular anomalies frequently coexist with placental mesenchymal dysplasia. In this case, placental mesenchymal dysplasia was associated with preterm labor at 33 weeks' gestation, fetal compromise, and a large abdominal mass with a large hepatic cyst that was de-roofed at exploratory laparotomy. The neonate remained critically ill with hypoxic ischaemic encephalopathy and coagulopathy and died despite intensive care. Biopsy and autopsy findings showed a large cystic mesenchymal hamartoma affecting the left lobe of the liver. This appears to be the 3rd histologically confirmed association of placental mesenchymal dysplasia with mesenchymal hamartoma of the liver in the English language literature.

Origin and outcome of pregnancies affected by androgenetic/biparental chimerism

BACKGROUND

Androgenetic diploid cells confined to the placenta have recently been reported in several cases of normally developed fetuses in association with placental mesenchymal dysplasia (PMD).

METHODS AND RESULTS

We investigated two singleton, mildly growth-restricted, female pregnancies ascertained on the basis of PMD. One case had liver hemangiomas and both infants had multiple skin hemangiomas. Post-natal development was normal. Molecular marker analysis confirmed the diagnosis of androgenetic and normal mixed cell populations in the placenta. Both cases derived from a single maternal genome (M1) and two distinct paternal genomes (P1 and P2). In one case, the androgenetic cell population contained both paternal genomes (P1P2), with one shared in common with the biparental (M1P1) population. In the second case, the androgenetic lineage showed complete homozygosity (P2P2) for a paternal genome not common to the biparental cell population.

CONCLUSION

These new PMD cases help to define the range of possible clinical presentations of androgenetic/biparental mosaicism or chimerism. Placentas with androgenetic/biparental chimeric cell populations may derive from a single tri-pronuclear (3PN) zygote in which one or more parental genomes are not equally apportioned to the daughter cells in the first cell division.

Clinical significance of placental examination in perinatal medicine

Complete pathologic evaluation of the placenta provides valuable information for perinatal care for the obstetrician, neonatologist, pediatrician, and family. The histopathology of the placenta can answer specific questions about in utero insults, give insight into management of subsequent pregnancies, and provide an assessment of the newborn risk. Placental pathology has been a key litigious informant in inferring timing of insults. Despite these well known advantages of placental pathologic examination, it remains an under-utilized part of perinatal medicine. This stems from a historically under-taught part of surgical and autopsy pathology resulting in inadequate reporting. This review will focus on the utility of the placental examination for fetal and maternal well-being. This review will be restricted to singleton births.

Androgenetic/biparental mosaicism causes placental mesenchymal dysplasia

BACKGROUND

Placental mesenchymal dysplasia (PMD) is a distinct syndrome of unknown aetiology that is associated with significant fetal morbidity and mortality. Intrauterine growth restriction is common, yet, paradoxically, many of the associated fetuses/newborns have been diagnosed with Beckwith-Wiedemann syndrome (BWS).

METHODS

We report two cases of PMD with high levels of androgenetic (complete paternal uniparental isodisomy) cells in the placenta and document, in one case, a likely androgenetic contribution to the fetus as well.

RESULTS

The same haploid paternal complement found in the androgenetic cells was present in coexisting biparental cells, suggesting origin from a single fertilisation event.

CONCLUSIONS

Preferential allocation of the normal cells into the trophoblast explains the absence of trophoblast overgrowth, a key feature of this syndrome. Interestingly, the distribution of androgenetic cells appears to differ from that reported for artificially created androgenetic mouse chimeras. Androgenetic mosaicism for the first time provides an aetiology for PMD, and may be a novel mechanism for BWS and unexplained intrauterine growth restriction.

Gestational trophoblastic diseases: recent advances in histopathologic diagnosis and related genetic aspects

Gestational trophoblastic disease refers to a spectrum of proliferative disorders of the placental trophoblast, with a wide range of histologic appearances and clinical behaviors. This review discusses the more recent developments in the diagnosis of these entities. Changes in criteria for the histologic diagnosis of these lesions due to earlier clinical diagnosis are reviewed, and the ability to make more accurate diagnoses due to the introduction of newer antibodies such as p57 is highlighted. A discussion of epithelioid trophoblastic tumor, a newly introduced tumor subtype, with its differential diagnosis from placental-site trophoblastic tumor and squamous cell carcinoma is also presented. Last, a brief discussion on the role of genetic studies and the future direction of research in elucidating the nature of this intriguing group of lesions is presented.

Twin pregnancy with a chimeric androgenetic and biparental placenta in one twin displaying placental mesenchymal dysplasia phenotype

OBJECTIVES

The aim was to report an unusual trizygotic pregnancy that resulted in live-born twins. The placenta of one twin had placental mesenchymal dysplasia (PMD), which resulted from a chimeric fusion of an androgenetic zygote and a normal biparental zygote. The literature review was summarized.

METHODS

The case was first detected by prenatal ultrasound, and was then followed by a histologic and detailed genetic investigation. The literature on PMD, complete hydatidiform moles (CHMs), and placental mosaicism and chimerism was also reviewed.

RESULTS

One placenta of a twin pregnancy was noted to be diffusely cystic and enlarged. The macroscopic and microscopic findings were consistent with the diagnosis of PMD; however, genetic findings confirmed confined placental chimerism involving a normal biparental 46,XY male conceptus and an androgenetic 46,XX complete hydatidiform mole.

CONCLUSIONS

This case represents a rare placental abnormality, PMD, which may have a diverse etiology. Therefore, detailed histologic and genetic analysis were performed for an accurate diagnosis.

Placental mesenchymal dysplasia associated with fetal aneuploidy

OBJECTIVES

To describe three cases of placental mesenchymal dysplasia (PMD) associated with abnormal karyotype and review the cases reported in the literature.

METHODS

The cases were retrieved from the files of three different institutions. A search of the English language literature was performed using Medline database.

RESULTS

Placental abnormalities suggestive of molar changes were seen on the prenatal ultrasound scans. Histologically, the cases had large, hydropic stem villi with myxomatous stroma, cistern formation and 'chorangiomatoid' changes. The placental and fetal karyotypes identified were trisomy 13 (47,XX,t(1:13)(q32;q32)+ 13); Klinefelter syndrome (47,XXY) and triploidy (69,XXX). Including these 3 cases, of 66 reported cases, 51 (78%) were female and 14 (22%) male (ratio 3.6:1); the karyotype was normal in 32/36 (89%) and abnormal in 4/36 (11%); Beckwith-Wiedemann syndrome was confirmed or suspected in 15/66 (23%). Excluding termination of pregnancies, intrauterine death occurred in 18/54 (33%) cases.

CONCLUSION

Molar ultrasonographic appearances associated with increased maternal serum alpha-fetoprotein but normal, or slightly elevated, levels of ss human Chorionic Gonadotrophin should raise the clinical suspicion of PMD. The diagnosis of this condition should not be disregarded when an abnormal fetus and/or an abnormal karyotype are demonstrated.