- Müllerian carcinosarcoma is currently regarded as a metaplastic (sarcomatous) carcinoma. Only five cases of pure ovarian adenocarcinoma recurring as carcinosarcoma have been documented in the literature. There are no documented cases of endometrial adenocarcinoma recurring as metaplastic carcinoma. We report of a case of endometrial adenocarcinoma, endometrioid type, recurring as metaplastic carcinoma showing sarcomatous differentiation. The tumor evolution in this case supports the prevailing opinion that Müllerian carcinosarcomas are derived from carcinomas and represent tumor progression.