Reproducibility of Morphologic Parameters of the International Endocervical Adenocarcinoma Criteria and Classification System and Correlation With Clinicopathologic Parameters: A Multi-Institutional Study.

Endocervical adenocarcinomas (ECAs) have been recently reclassified according to their morphologic features linked to etiology by the International Endocervical Adenocarcinoma Criteria and Classification (IECC) and this system is adopted by WHO 2020. This classification separates the ECAs as human papillomavirus (HPV)-associated (HPVA) and HPV-independent (HPVI) subtypes. According to WHO 2020, high risk (HR)-HPV association can be histologically recognized by the presence of luminal mitoses and apoptosis. Therefore, investigating the reproducibility of the morphologic criteria of this new classification will be important in observing the recognizability of tumor types. Full slide sets of 94 ECAs were collected from 4 institutions in Turkey and reclassified on the basis of IECC/WHO 2020 criteria and the presence or absence of HR-HPV. HR-HPV presence was confirmed by HPV DNA in situ hybridization, p16 immunohistochemistry and in conflicted cases with real time-polymerase chain reaction. The final diagnoses were given based on the combination of the histologic evaluation and ancillary test results. Our cohort was consisted of 73.4% HPVA and 26.6% HPVI cases. According to the WHO 2020 criteria 92.7% of HPVAs and 88% of HPVIs were easily classified. HPV DNA in situ hybridization was positive in 91.3% of the HPVAs and p16 was positive in all HPVAs, whereas was also positive in 8% of the HPVIs. In conclusion, most of the ECAs can be diagnosed by their characteristic morphologic features by the WHO 2020 criteria. However, we want to emphasize that mitosis/apoptosis criteria may not be helpful especially in mucinous ECAs and ancillary tests for HR-HPV should be used in challenging cases.