Cervical stromal involvement by endometrial 'hyperplasia': a previously unreported phenomenon with recommendations to report as stage II endometrial carcinoma.

A subtle 'burrowing' pattern of cervical stromal involvement by low-grade endometrioid adenocarcinoma of the uterine corpus is described in the literature. We report a small case series in which this pattern of cervical stromal involvement, warranting a diagnosis of endometrioid adenocarcinoma in the cervix, occurred in association with sometimes subtle endometrioid proliferations within the endometrium which fall short of the criteria for endometrioid adenocarcinoma and are in keeping with atypical hyperplasia or hyperplasia without atypia. In reporting this phenomenon, which has not been described previously, we highlight the importance of immunohistochemistry in the differential diagnosis, particularly in the exclusion of primary cervical glandular lesions, including those of mesonephric type. We discuss the differential with primary endometrioid adenocarcinoma (including minimal deviation type) of the cervix and other lesions and stress the importance of sampling the endometrium and lower uterine segment in their entirety in order to exclude an atypical hyperplasia or an adenocarcinoma in these locations. Although the pathogenesis of the cervical lesion we report is controversial, we believe that it is most likely a result of spread from the endometrium and results in the unusual occurrence of the malignant nature of the lesion being only apparent in the secondary rather than the primary lesion. We provide recommendations for reporting such cases and recommend designating them as stage II endometrial carcinoma, although the prognostic and management implications of such cases will only be clear once further cases with follow-up are reported.
(Copyright © 2021 Royal College of Pathologists of Australasia. Published by Elsevier B.V. All rights reserved.)