Mesonephric-like Adenocarcinoma of the Uterine Corpus: Comprehensive Analyses of Clinicopathological, Molecular, and Prognostic Characteristics With Retrospective Review of 237 Endometrial Carcinoma Cases

Background/Aim: Uterine mesonephric-like adenocarcinoma (MLA) is a rare malignant tumor of the female genital tract. Patients and Methods: We reviewed 237 endometrial carcinoma cases and investigated the clinicopathological and molecular characteristics of uterine MLA. Results: We found that 3.0% (7/237) of the endometrial carcinoma cases were MLAs. Compared to endometrial endometrioid carcinoma, MLA showed larger tumor size, deeper myometrial invasion, increasingly advanced-stage disease, and more frequent lymphovascular space invasion. All MLAs exhibited architectural diversity, compactly aggregated small tubules, eosinophilic intraluminal secretions, overlapped and angulated nuclei, scant cytoplasm, and presence of spindle cells. All the MLAs expressed at least two mesonephric markers. All except one MLA harbored activating Kirsten rat sarcoma viral oncogene homolog mutations. All patients with MLA developed postoperative metastases. MLA had the lowest progression-free survival rate among different histological types of endometrial carcinoma. Conclusion: Uterine MLA is a highly aggressive gynecological malignancy, showing unique morphological and molecular features, frequent recurrences and metastases, as well as poor prognosis.