p57-discordant villi in hydropic products of conception: a clinicopathological study of 70 cases

STK40 inhibits trophoblast fusion by mediating COP1 ubiquitination to degrade P57Kip2

BACKGROUND

The syncytiotrophoblast (SCT) layer in the placenta serves as a crucial physical barrier separating maternal-fetal circulation, facilitating essential signal and substance exchange between the mother and fetus. Any abnormalities in its formation or function can result in various maternal syndromes, such as preeclampsia. The transition of proliferative villous cytotrophoblasts (VCT) from the mitotic cell cycle to the G0 phase is a prerequisite for VCT differentiation and their fusion into SCT. The imprinting gene P57Kip2, specifically expressed in intermediate VCT capable of fusion, plays a pivotal role in driving this key event. Moreover, aberrant expression of P57Kip2 has been linked to pathological placental conditions and adverse fetal outcomes.

METHODS

Validation of STK40 interaction with P57Kip2 using rigid molecular simulation docking and co-immunoprecipitation. STK40 expression was modulated by lentivirus in BeWo cells, and the effect of STK40 on trophoblast fusion was assessed by real-time quantitative PCR, western blot, immunofluorescence, and cell viability and proliferation assays. Co-immunoprecipitation, transcriptome sequencing, and western blot were used to determine the potential mechanisms by which STK40 regulates P57Kip2.

RESULTS

In this study, STK40 has been identified as a novel interacting protein with P57Kip2, and its expression is down-regulated during the fusion process of trophoblast cells. Overexpressing STK40 inhibited cell fusion in BeWo cells while stimulating mitotic cell cycle activity. Further experiments indicated that this effect is attributed to its specific binding to the CDK-binding and the Cyclin-binding domains of P57Kip2, mediating the E3 ubiquitin ligase COP1-mediated ubiquitination and degradation of P57Kip2. Moreover, abnormally high expression of STK40 might significantly contribute to the occurrence of preeclampsia.

CONCLUSIONS

This study offers new insights into the role of STK40 in regulating the protein-level homeostasis of P57Kip2 during placental development.

Appraisal of hydatidiform mole incidence and registration rates in Ireland following the establishment of a National Gestational Trophoblastic Disease Registry

AIMS

This study aimed to re-evaluate the incidence of hydatidiform mole (HM) and determine gestational trophoblastic disease (GTD) registration rates in Ireland following the establishment of the National GTD Registry in 2017.

METHODS

We performed a 3-year retrospective audit of HM cases (January 2017 to December 2019) reported in our centre. In 2019, we surveyed Irish pathology laboratories to determine the number of HMs diagnosed nationally and compared this data to that recorded in the National GTD Registry. Additionally, we compared both local and national HM incidence rates to those reported internationally.

RESULTS

In the 3-year local audit, we identified 87 HMs among 1856 products of conception (POCs) providing a local HM incidence rate of 3.92 per 1000 births. The 1-year pathology survey recorded 170 HMs in 6008 POCs, yielding a national incidence rate of 2.86 per 1000 births. Importantly, the local HM incidence rate exceeded the national incidence rate by 37% and the local partial HM incidence (1 in 296 births) was 64% higher than the nationally incidence rate (1 in 484 births). Notably, 42% of the HM and atypical POCs diagnosed nationally were not reported to the National GTD Registry.

CONCLUSIONS

Our study reveals increased HM incidence rates both locally and nationally compared with previous Irish studies. The higher local PHM incidence may reflect more limited access to ploidy analysis in other pathology laboratories nationally. Significantly, almost half of the women with diagnosed or suspected HM were not registered with the National GTD Centre.

Practical guidelines of the EOTTD for pathological and genetic diagnosis of hydatidiform moles

Hydatidiform moles are rare and thus most pathologists and geneticists have little experience with their diagnosis. It is important to promptly and correctly identify hydatidiform moles given that they are premalignant disorders associated with a risk of persistent gestational trophoblastic disease and gestational trophoblastic neoplasia. Improvement in diagnosis can be achieved with uniformization of diagnostic criteria and establishment of algorithms. To this aim, the Pathology and Genetics Working Party of the European Organisation for Treatment of Trophoblastic Diseases has developed guidelines that describe the pathological criteria and ancillary techniques that can be used in the differential diagnosis of hydatidiform moles. These guidelines are based on the best available evidence in the literature, professional experience and consensus of the experts' group involved in its development.

Androgenetic/biparental mosaicism in a diploid mole-like conceptus: report of a case with triple paternal contribution

Hydatidiform moles (HMs) are divided into two types: partial hydatidiform mole (PHM) which is most often diandric monogynic triploid and complete hydatidiform mole (CHM) which is most often diploid androgenetic. Morphological features and p57 immunostaining are routinely used to distinguish both entities. Genetic analyses are required in challenging cases to determine the parental origin of the genome and ploidy. Some gestations cannot be accurately classified however. We report a case with atypical pathologic and genetic findings that correspond neither to CHM nor to PHM. Two populations of villi with divergent and discordant p57 expression were observed: morphologically normal p57 + villi and molar-like p57 discordant villi with p57 + stromal cells and p57 - cytotrophoblasts. Genotyping of DNA extracted from microdissected villi demonstrated that the conceptus was an androgenetic/biparental mosaic, originating from a zygote with triple paternal contribution, and that only the p57 - cytotrophoblasts were purely androgenetic, increasing the risk of neoplastic transformation.

When to Consult a Geneticist Specialising in Gestational Trophoblastic Disease

BACKGROUND

Gestational trophoblastic disease comprises hydatidiform moles and a rare group of malignancies that derive from trophoblasts. Although there are typical morphological features that may distinguish hydatidiform moles from non-molar products of conception, such features are not always present, especially at early stages of pregnancy. Furthermore, mosaic/chimeric pregnancies and twin pregnancies make pathological diagnosis challenging while trophoblastic tumours can also pose diagnostic problems in terms of their gestational or non-gestational origin.

OBJECTIVES

The aim of this study was to show that ancillary genetic testing can be used to aid diagnosis and clinical management of GTD.

METHODS

Each author identified cases where genetic testing, including short tandem repeat (STR) genotyping, ploidy analysis, next-generation sequencing, and immunostaining for p57, the product of the imprinted gene CDKN1C, facilitated accurate diagnosis and improved patient management. Representative cases were chosen to illustrate the value of ancillary genetic testing in different scenarios.

OUTCOME

Genetic analysis of placental tissue can aid in determining the risk of developing gestational trophoblastic neoplasia, facilitating discrimination between low risk triploid (partial) and high risk androgenetic (complete) moles, discriminating between a hydatidiform mole twinned with a normal conceptus and a triploid conception and identification of androgenetic/biparental diploid mosaicism/chimerism. STR genotyping of placental tissue and targeted gene sequencing of patients can identify women with an inherited predisposition to recurrent molar pregnancies. Genotyping can distinguish gestational from non-gestational trophoblastic tumours using tissue or circulating tumour DNA and can also identify the causative pregnancy which is the key prognostic factor for placental site and epithelioid trophoblastic tumours.

CONCLUSIONS AND OUTLOOK

STR genotyping and p57 immunostaining have been invaluable to the management of gestational trophoblastic disease in many situations. The use of next-generation sequencing and of liquid biopsies is opening up new pathways for GTD diagnostics. Development of these techniques has the potential to identify novel biomarkers of GTD and further refine diagnosis.

The Presence of the Autophagic Markers LC3B and Sequestosome 1/p62 in the Hydatidiform Mole

Autophagy is implicated in normal pregnancy and various pathologic pregnancy conditions. Its presence in hydatidiform moles (HM) is unknown. We immunohistochemically studied 36 HM for LC3B and p62 to precisely determine their expression in the decidua, endometrium, and villi. Nineteen nonmolar pregnancies were also studied. LC3B was found in almost half of the villi and p62 was found in almost all villi. LC3B expression was significantly higher in complete HM than in partial HM. LC3B showed different expression patterns in trophoblast layers. LC3B and p62 expression was higher in molar than nonmolar pregnancies. Autophagic markers are present in HM and their expression differs between complete and partial moles.

Challenges in diagnosing hydatidiform moles: a review of promising molecular biomarkers

INTRODUCTION

Hydatidiform moles (HMs) are pathologic conceptions with unique genetic bases and abnormal placental villous tissue. Overlapping ultrasonographical and histological manifestations of molar and non-molar (NM) gestations and HMs subtypes makes accurate diagnosis challenging. Currently, immunohistochemical analysis of p57 and molecular genotyping have greatly improved the diagnostic accuracy.

AREAS COVERED

The differential expression of molecular biomarkers may be valuable for distinguishing among the subtypes of HMs and their mimics. Thus, biomarkers may be the key to refining HMs diagnosis. In this review, we summarize the current challenges in diagnosing HMs, and provide a critical overview of the recent literature about potential diagnostic biomarkers and their subclassifications. An online search on PubMed, Web of Science, and Google Scholar databases was conducted from the inception to 1 April 2022.

EXPERT OPINION

the emerging biomarkers offer new possibilities to refine the diagnosis for HMs and pregnancy loss. Although the additional studies are required to be quantified and investigated in clinical trials to verify their diagnostic utility. It is important to explore, validate, and facilitate the wide adoption of newly developed biomarkers in the coming years.

Rare Complete Hydatidiform Mole With p57 Expression in Villous Mesenchyme: Case Report and Review of Discordant p57 Expression in Hydatidiform Moles

Complete hydatidiform mole (CHM) is a premalignant proliferative disease of the placenta characterized by misexpression of imprinted gene products, most notably p57. The majority of CHM exhibit immunohistochemical absence of p57 protein in villous mesenchyme (VM) and cytotrophoblast (CT) and are thus p57 VM/CT concordant. However, some gestations show loss of p57 in only VM or CT, either in all chorionic villi or a subset thereof (VM/CT discordant). Here, we present a rare case of a p57 VM/CT-discordant CHM with diffuse retention of p57 expression in VM but complete absence in CT. Histologically, the case exhibited typical features of CHM including trophoblast hyperplasia and severe nuclear atypia, but was unusual in the presence of gestational membranes identified ultrasonographically and histologically. Ploidy determination by FISH and genotyping by short tandem repeat analyses showed that this was a diploid gestation with variable allelic ratios and with an androgenetic lineage, similar to previously reported p57 VM/CT-discordant cases.

Advances in the diagnosis and early management of gestational trophoblastic disease

Gestational trophoblastic disease describes a group of rare pregnancy related disorders that span a spectrum of premalignant and malignant conditions. Hydatidiform mole (also termed molar pregnancy) is the most common form of this disease. Hydatidiform mole describes an abnormal conceptus containing two copies of the paternal genome, which is classified as partial when the maternal genome is present or complete when the maternal genome is absent. Hydatidiform mole typically presents in the first trimester with irregular vaginal bleeding and can be suspected on ultrasound but confirmation requires histopathological evaluation of the products of conception. Most molar pregnancies resolve without treatment after uterine evacuation, but occasionally the disease persists and develops into gestational trophoblastic neoplasia. Close monitoring of women after molar pregnancy, with regular measurement of human chorionic gonadotrophin concentrations, allows for early detection of malignancy. Given the rarity of the disease, clinical management and treatment is best provided in specialist centres where very high cure rates are achievable. This review looks at advances in the diagnosis and early management of gestational trophoblastic disease and highlights updates to disease classification and clinical guidelines. Use of molecular genotyping for improved diagnostic accuracy and risk stratification is reviewed and future biomarkers for the earlier detection of malignancy are considered.

Association of Placental Mesenchymal Dysplasia With a Live Female Fetus and Complete Hydatidiform Mole: Report of a Challenging Case Confirmed by Molecular Genotyping Analysis

Placental mesenchymal dysplasia (PMD) and complete hydatidiform mole (CHM) with a coexisting fetus are 2 rare placental abnormalities characterized by lacunar placenta and presence of an embryo on ultrasound examination. We report the case of a 34-yr-old woman referred at 32.6 weeks of gestation because of a multicystic placenta. A caesarean section was performed at 39.1 weeks of gestation giving birth to a 2905 g normal female infant. Pathological examination revealed macroscopic and microscopic morphological, and immunohistological features of PMD in the main placenta, and features of CHM in a separate placental mass. Fluorescent in situ hybridization and molecular genotyping analyses showed diandric diploidy in the CHM component and androgenetic/biparental mosaicism in the PMD component, confirming the association of PMD and CHM with a live infant. There was no progression to gestational trophoblastic neoplasia during follow-up for the mother, or any sign of Beckwith-Wiedemann syndrome or hepatic tumor in the child.

Genetics of gestational trophoblastic disease

The abnormal pregnancies complete and partial hydatidiform mole are genetically unusual, being associated with two copies of the paternal genome. Typical complete hydatidiform moles (CHMs) are diploid and androgenetic, while partial hydatidiform moles (PHMs) are diandric triploids. While diagnosis can usually be made on the basis of morphology, ancillary techniques that exploit their unusual genetic origin can be used to facilitate diagnosis. Genotyping and p57 immunostaining are now routinely used in the differential diagnosis of complete and partial hydatidiform moles, for investigating unusual mosaic or chimeric products of conception with a molar component and identifying the rare diploid, biparental HMs associated with an inherited predisposition to molar pregnancies. Genotyping also plays an important role in the differential diagnosis of gestational and non-gestational trophoblastic tumours and identification of the causative pregnancy where tumours are gestational. Recent developments include the use of cell-free DNA for non-invasive diagnosis of these conditions.

Discovery of inverted discordant p57 expression in random clusters of dysmorphic chorionic villi of third trimester placentas suggests a more common occurrence of such phenomenon than initially described

INTRODUCTION

Inverted discordant p57 expression in chorionic villi, characterized by a loss of nuclear staining in cytotrophoblast with retained staining in villous stromal cells, is rarely described. Following an incidental finding of such peculiar staining pattern in rare clusters of dysmorphic chorionic villi (DCV) in a perinatal autopsy case, we reviewed our archived cases of third trimester placentas with DCV to systematically analyze these curious foci.

METHODS

Histopathological features and p57 expression of 26 placentas with DCV were carefully studied by light microscopy and p57 immunohistochemistry. p57 pattern of expression was correlated with a comprehensive list of maternal, fetal, and placental features to reveal potential associations.

RESULTS

Inverted discordant p57 expression was observed in 17/26 (65.4%) cases, encompassing all cases with aberrant p57 immunostaining in this series. Among the many features investigated, only the focality (occurring as a single focus) of DCV (Fisher's exact test, p = 0.008) and small cluster size of ≤30 villi (Fisher's exact test, p = 0.034) correlated significantly with inverted discordant p57 staining. Other common features of DCV with inverted discordant p57 expression include larger villous size compared with surrounding tertiary villi (13/17, 76.4%), prominent but not hyperplastic and focally to moderately hyperplastic syncytiotrophoblast (17/21, 80.9%), abnormal shapes/irregular contours (17/22, 77.3%), and markedly hypovascular villous stroma (11/17, 64.7%). No distinctive maternal or fetal features were observed.

DISCUSSION

Inverted discordant p57 expression in DCV of third trimester placentas is likely underreported, and might not be an unusual occurrence outside of suspected molar specimens.