Combination of immunohistochemistry and ploidy analysis to assist histopathological diagnosis of molar diseases

Diagnostic Utility of TSSC3 and RB1 Immunohistochemistry in Hydatidiform Mole

The general notion of complete hydatidiform moles is that most of them consist entirely of paternal DNA; hence, they do not express p57, a paternally imprinted gene. This forms the basis for the diagnosis of hydatidiform moles. There are about 38 paternally imprinted genes. The aim of this study is to determine whether other paternally imprinted genes could also assist in the diagnostic approach of hydatidiform moles. This study comprised of 29 complete moles, 15 partial moles and 17 non-molar abortuses. Immunohistochemical study using the antibodies of paternal-imprinted (RB1, TSSC3 and DOG1) and maternal-imprinted (DNMT1 and GATA3) genes were performed. The antibodies' immunoreactivity was evaluated on various placental cell types, namely cytotrophoblasts, syncytiotrophoblasts, villous stromal cells, extravillous intermediate trophoblasts and decidual cells. TSSC3 and RB1 expression were observed in all cases of partial moles and non-molar abortuses. In contrast, their expression in complete moles was identified in 31% (TSSC3) and 10.3% (RB1), respectively (p < 0.0001). DOG1 was consistently negative in all cell types in all cases. The expressions of maternally imprinted genes were seen in all cases, except for one case of complete mole where GATA3 was negative. Both TSSC3 and RB1 could serve as a useful adjunct to p57 for the discrimination of complete moles from partial moles and non-molar abortuses, especially in laboratories that lack comprehensive molecular service and in cases where p57 staining is equivocal.

Pathological features of early pregnancy disorders in women living at high altitude in KSA

Objectives

Pregnancy at high altitudes is relatively challenging because of hypobaric hypoxia, which is associated with a smaller uterine artery diameter and diminished blood flow. Here, we investigated the histopathological characteristics of early pregnancy disorders among pregnant women living in a high-altitude region (approximately 2200 m above sea level).

Methods

This cross-sectional study used retrospective data collection from a single tertiary hospital in a high-altitude region in KSA. Age and histopathology were analyzed in 495 women diagnosed with early pregnancy disorders (mainly miscarriage) in 2018-2020.

Results

Approximately one-fifth of pregnancies in this high-altitude region were lost before 24 weeks' gestation, whereas 1150/6044 experienced miscarriage; 495 samples from those participants were sent for histopathological analysis. A total of 269 (54.34%) patients were younger than 35 years. Missed miscarriages accounted for 49.3% of miscarriages, followed by inevitable miscarriages (34.2%), which had a relatively higher frequency among mothers older than 35 years. The correlation between age and inevitable miscarriage was significant; ectopic pregnancy was diagnosed in 6.8%, molar pregnancy was detected in 6.26%, and blighted ovum was observed in 3.4%.

Conclusion

The miscarriage rate in this high-altitude region was 19% of all pregnancies. Approximately half of the affected women were in their 30s. Missed miscarriage cases were relatively high in this region. The percentage of molar pregnancy was higher than those reported in prior studies, thus suggesting a need for monitoring and genetic workup practices. Furthermore, studies involving a larger population at high altitudes will be crucial for further risk assessment in addition to national studies on women living at sea level.

Complementary role of p57kip2 immunostaining in diagnosing hydatidiform mole subtypes

OBJECTIVES

Gestational trophoblastic disease comprises of a spectrum of pregnancy-related tumours which includes complete (CHM) and partial hydatidiform moles (PHM). Accurate diagnosis and subclassification of HM subtypes are crucial as prognosis differs. Histopathological examination using haemotoxylin and eosin (H&E) staining remains the basis for diagnosing HM, with only 80% accuracy. p57kip2 is a cyclin-dependent kinase inhibitor (CDKI) protein and is strongly paternally imprinted, being expressed from maternal allele. Therefore, complete mole (CHM) with only paternal genome has nearly absent expression of p57kip2 compared to partial mole (PHM) having both paternal and maternal genomes. This study is aimed to determine usefulness of p57kip2 immunohistochemistry (IHC) analysis in the diagnosis of HM subtypes.

METHODS

A total of 82 archived paraffin embedded HM tissues with subtypes classified based on H&E staining - 39 (47.5%) CHM, 41 (50.0%) PHM and two (2.43%) unclassified molar pregnancy were retrieved. All tissue samples were subjected for p57kip2 IHC analysis and HM subtypes were then reclassified.

RESULTS

A total of 66 cases (80.5%) were re-classified as CHM, 14 cases (17.1%) as PHM and two cases (2.4%) were decidual and cystic tissues. Analysis using p57kip2 immunostaining showed a diagnostic discrepancy of 33.0% from routine H&E staining and helps to improve the characterisation of the HM subtypes specifically at early gestations which have less distinctive morphologies.

CONCLUSIONS

IHC using p57kip2 monoclonal antibody should be considered as a routine ancillary test to H&E in improving the diagnosis of HM subtypes particularly in developing countries with limited resources.

DNA flow cytometric analysis in variable types of hydropic placentas

BACKGROUND

Differential diagnosis between complete hydatidiform mole, partial hydatidiform mole and hydropic abortion, known as hydropic placentas is still a challenge for pathologists but it is very important for patient management.

OBJECTIVE

We analyzed the nuclear DNA content of various types of hydropic placentas by flowcytometry.

MATERIALS AND METHODS

DNA ploidy analysis was performed in 20 non-molar (hydropic and non-hydropic spontaneous abortions) and 20 molar (complete and partial moles), formalin-fixed, paraffin-embedded tissue samples by flow cytometry. The criteria for selection were based on the histopathologic diagnosis.

RESULTS

Of 10 cases histologically diagnosed as complete hydatiform mole, 9 cases yielded diploid histograms, and 1 case was tetraploid. Of 10 partial hydatidiform moles, 8 were triploid and 2 were diploid. All of 20 cases diagnosed as spontaneous abortions (hydropic and non-hydropic) yielded diploid histograms.

CONCLUSION

These findings signify the importance of the combined use of conventional histology and ploidy analysis in the differential diagnosis of complete hydatidiform mole, partial hydatidiform mole and hydropic abortion.

Ki-67 expression in hydatidiform moles and hydropic abortions

Background

Differential diagnosis of hydatidiform moles from non-molar specimens as well as their sub-classification such as complete and partial hydatidiform moles are important for clinical management and accurate risk assessment for persistent gestational trophoblastic disease, but diagnosis based solely on histomorphology suffers from poor interobserver and intraobserver reproducibility.

Objectives

This study was undertaken to determine whether the expression of Ki-67 protein could differentiate these entities.

Materials and Methods

We performed Ki-67 immunohistochemical staining in 19 molar (8 partial and 11 complete moles) and 10 non-molar (hydropic abortions) formalin-fixed, paraffin-embedded tissue samples. Ploidy analysis using flow cytometry had confirmed diploidy in hydropic abortions and complete moles and triploidy in partial moles.

Results

Ki-67 immunoreactivity was assessed in villous cytotrophoblasts, syncytiotrophoblasts and stromal cells. Positive cells were found to be restricted mostly to the villous cytotrophoblasts, while syncytiotrophoblasts showed an absence of immunostaining for Ki-67, and occasional weak nuclear staining was seen in the stromal cells. There was a significant difference in Ki-67 immunoreactivity of cytotrophoblastic cells between hydropic abortions and complete moles (P < 0.001), hydropic abortions and partial moles (P = 0.002) and also between complete and partial moles (P < 0.001). On the other hand, there is significant overlap in the Ki-67 immunoreactivity between complete and partial moles (++ staining category) and between partial moles and hydropic abortions (+ staining category).

Conclusions

Despite the significant differences , Ki-67 immunostaining could not be helpful in distinguishing molar placentas from hydropic abortions as well as partial from complete hydatidiform moles, because there are considerable overlaps between results in different categories.