A Multiinstitutional Consensus Study on the Pathologic Diagnosis of Endometrial Hyperplasia and Carcinoma

Background: The purpose of this study was to examine the reproducibility of both the diagnosis of endometrial hyperplasia (EH) or adenocarcinoma, and the histologic grading (HG) of endometrioid adenocarcinoma (EC). Methods: Ninety-three cases of EH or adenocarcinomas were reviewed independently by 21 pathologists of the Gynecologic Pathology Study Group. A consensus diagnosis was defined as agreement among more than two thirds of the 21 pathologists. Results: There was no agreement on the diagnosis in 13 cases (14.0%). According to the consensus review, six of the 11 EH cases (54.5%) were diagnosed as EH, 48 of the 57 EC cases (84.2%) were EC, and 5 of the 6 serous carcinomas (SC) (83.3%) were SC. There was no consensus for the 6 atypical EH (AEH) cases. On the HG of EC, there was no agreement in 2 cases (3.5%). According to the consensus review, 30 of the 33 G1 cases (90.9%) were G 1, 11 of the 18 G2 cases (61.1%) were G2, and 4 of the 4 G3 cases (100.0%) were G3. Conclusions: The consensus study showed high agreement for both EC and SC, but there was no consensus for AEH. The reproducibility for the HG of G2 was poor. We suggest that simplification of the classification of EH and a two-tiered grading system for EC will be necessary.