These include the common and readily treatable well-differentiated endometrioid adenocarcinoma, as well as the more aggressive uterine papillary serous carcinoma and uterine clear-cell carcinoma. Endometrial stromal sarcomas originate from the connective tissues of the endometrium, and are far less common than endometrial carcinomas. Malignant mixed Müllerian tumors are rare endometrial tumors which show both glandular (carcinomatous) and stromal (sarcomatous) differentiation – carcinosarcoma behaves similar to a high grade carcinoma, and it is felt to be of epithelial origin rather than true sarcoma.