[Molecular classification and clinicopathological features of endometrial carcinoma]

Objective: To investigate the molecular classification and clinicopathological features of endometrial carcinoma(EC). Methods: One hundred cases of EC diagnosed in the Department of Pathology, Tianjin Central Hospital of Gynecology and Obstetrics from November 2020 to November 2021 were selected. Sanger sequencing and immunohistochemical staining were used for molecular classification according to the 5th WHO classification. The clinicopathological characteristics of each molecular subtype was analyzed. Results: The 100 EC patients had a mean age of 53 years (range 26 to 72 years). There were 10 cases of POLE mutation (POLE mut), including two cases (2/10) of "binary-classifier" EC, two cases (2/10) of FIGO Grade 3 endometrioid endometrial carcinoma (G3-EEC), and three cases (3/10) of other high-grade subtypes. There were 38 cases of mismatch repair deficiency (dMMR), including one case (1/38, 2.6%) of "binary-classifier" EC and 36 cases (36/38, 94.7%) were EEC. Twenty-one cases (21/38, 55.3%) showed simultaneous loss of expression of MLH1 and PMS2, and 20 cases (20/21, 95.2%) were positive for MLH1 methylation, indicating that they were sporadic EC. Six patients (6/38, 15.8%) were tested for germline detection of Lynch syndrome (LS) related genes, and one patient was LS-related EC. There were 44 cases of non-specific molecular profile (NSMP), including 34 cases (34/44, 77.3%) of G1-2 EEC and seven cases (7/44, 15.9%) of G3-EEC. There were eight cases of p53 abnormality (p53 abn), including four cases (4/8) of G3-EEC, two cases (2/8) of other high-grade subtypes, and one patient had hereditary breast cancer and ovarian cancer syndrome. Conclusions: Correct interpretation of POLE mutation, MMR and p53 immunohistochemistry is the key of molecular classification. The interpretation must strictly follow standard diagnostic procedures and specifications to ensure the accuracy of molecular classification.