# Discrepancies Between Pathological Distinction and DNA Genotyping in the Diagnosis of Hydatidiform Moles

## TL;DR

This study shows that combining DNA genotyping with traditional histology improves the accuracy of diagnosing complete and partial hydatidiform moles.

## Contribution

The study demonstrates that DNA genotyping enhances diagnostic accuracy when combined with p57kip2 immunohistochemistry and histology for hydatidiform moles.

## Key findings

- DNA genotyping identified decidua in cases initially diagnosed as complete or partial hydatidiform moles.
- Pathological diagnosis had 100% sensitivity but only 33% specificity when compared to DNA genotyping results.
- Most cases showed homodisomy, indicating a paternal origin of the genetic material in hydatidiform moles.

## Abstract

Introduction

The incidence of invasive moles and choriocarcinoma after uterine evacuation differs between a complete hydatidiform mole (CHM) and a partial hydatidiform mole (PHM). Accurately distinguishing between these two types is important. This study aimed to investigate diagnostic differences in hydatidiform moles using p57kip2 immunohistochemistry and DNA genotyping analysis in trophoblastic tissue.

Materials and methods

Twenty-four patients who underwent uterine evacuation or total hysterectomy for suspected hydatidiform moles between 2013 and 2022 were included in this study. Pathologists performed p57kip2 immunohistochemistry in addition to hematoxylin and eosin staining. A DNA genotyping analysis was performed on hydatidiform villus tissue and blood samples from patients and their partners (if possible) to differentiate between CHM and PHM.

Results

Of the 16 CHM cases diagnosed histologically, one was diagnosed as decidua by DNA genotyping. Of the eight PHM cases diagnosed histologically because of positive p57kip2 immunohistochemistry, four were diagnosed as CHM by DNA genotyping, and two were diagnosed as decidua. The sensitivity, specificity, positive predictive value, and negative predictive value of the pathological diagnosis of the 21 cases, excluding the three cases diagnosed as decidua by DNA testing, were 100%, 33%, 71.4%, and 28.6%, respectively (P = 0.0183, Pearson’s chi-square test). Of the 24 cases, blood samples were obtained from the partners in 15 cases. Of the 15 cases, 12 were homodisomy and three were heterodisomy.

Conclusions

Hematoxylin and eosin staining and p57kip2 immunohistochemistry are useful tools for differentiating CHM from PHM, but combining them with DNA genotyping analysis leads to a more accurate and reliable diagnosis.