Mesonephric-like Differentiation of Endometrial Endometrioid Carcinoma: Clinicopathological and Molecular Characteristics Distinct from Those of Uterine Mesonephric-like Adenocarcinoma.

Sujin Park,Go Eun Bae,Hyun-Soo Kim,Jiyoung Kim

doi:10.3390/diagnostics11081450

Abstract

When diagnosing endometrial carcinoma cases, we encountered histological features that strikingly resembled uterine mesonephric-like adenocarcinoma (MLA), but the differential diagnosis remained challenging after performing immunostaining. Considering the aggressive biological behavior and poor prognosis of uterine MLA, we believe that the accurate recognition of mesonephric-like differentiation (MLD) is important in the diagnosis of endometrial carcinoma. We aimed to investigate the clinicopathological and molecular characteristics of such cases and compared them with those of uterine MLAs. Five patients diagnosed with endometrioid carcinoma (EC) with MLD were included in this study. Histological evaluation, immunostaining, and targeted sequencing were performed. All five tumors showed typical morphological features of MLA, including densely aggregated tubular structures, deep basophilia under low-power magnification microscopy, eosinophilic intraluminal secretions, and diverse growth patterns. Immunostaining revealed moderate-to-strong nuclear immunoreactivity for estrogen and progesterone receptors in more than 50% tumor cells. The staining intensities and proportions of PAX2 and GATA3 were variable. None of the tumors harbored KRAS mutations. Considering the prognostic implications, ancillary tests, including immunostaining and targeted sequencing, should be performed to accurately differentiate between endometrial EC-MLD and uterine MLA.

Highlights

Endometrial carcinoma is the most common gynecological malignancy, and its incidence and mortality are increasing in developed countries [1]
Strong nuclear GATA3 immunoreactivity was observed in two cases, with staining proportions of 10% (Figure 4, lower panel) and
The areas that were positive for PAX2 and GATA3 were negative for hormone receptors

Summary

Introduction

Endometrial carcinoma is the most common gynecological malignancy, and its incidence and mortality are increasing in developed countries [1]. MA typically arises in the uterine cervix and vagina, but several cases of MA arising in the upper female genital tract have been documented [4,6,7,8,10,15,16,17,18,19]. Since their association with mesonephric remnants has not been firmly established, MA of the uterine corpus and ovary has been referred to in the literature as mesonephric-like adenocarcinoma (MLA) [15,17]. It has recently been shown that uterine MLAs show more aggressive biological behavior and worse prognosis than other histological subtypes of endometrial carcinoma [4]

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