Pelvic Carcinosarcoma Showing a Diverse Histology and Hierarchical Gene Mutation with a Common Mutation to Endometrial Endometroid Carcinoma: A Case Report.

mutation-type endometrial cancer is characterized by an extremely high tumor mutation burden. Most mutation-type endometrial cancers are histologically endometrioid carcinomas, and mutation-type carcinosarcomas are rare among endometrial cancers. We report a case of endometrial and pelvic cancer in a 53-year-old woman who was analyzed using next-generating sequencing. The endometrial lesion harbored a p.T457del mutation with an elevated tumor mutation burden and low microsatellite instability. The pelvic lesion showed divergent histological features, consisting of high-grade endometrioid carcinoma, neuroendocrine carcinoma, and chondrosarcoma. In addition to the common mutation detected in the endometrial lesion, the pelvic lesion in each element showed additional gene mutations in a hierarchical manner. Therefore, it is indicated that the p.T457del mutation is a pathogenic mutation and may be related to mutation-induced carcinogenesis and divergent morphogenesis in endometrial cancer.