High-grade Endometrial Carcinoma With Serous and Colorectal Carcinoma-like Components: Unique Morphology in Correlation With Immunohistochemical and Molecular Findings.

Endometrial carcinoma with intestinal differentiation/colorectal carcinoma-like (CRC-like) features is rare with few cases reported to date. Those described are mainly endometrioid carcinomas with intestinal differentiation. We report a case of high-grade endometrial carcinoma with serous and intestinal/CRC-like components. The gross, histologic, immunohistochemical, and molecular features are described for both components of the tumor in the initial diagnostic biopsy and subsequent resection specimen. The diagnosis of primary endometrial carcinoma with serous and CRC-like components is supported by immunohistochemical and molecular findings, as well as clinical workup. The rarity of this phenomenon poses diagnostic challenges. In addition, the literature is reviewed with specific emphasis on the molecular and pathologic features of mixed endometrial carcinomas, including those with intestinal/CRC-like features.