Carcinosarcoma, light micrograph. Carcinosarcoma of the uterus is now considered to be a variant of endometrial carcinoma with metaplastic sarcomatous elements. It was previously known as malignant mixed mullerian tumour. It usually occurs in postmenopausal women. Microscopically, it has a biphasic appearance consisting of carcinomatous areas (dark purple glandular structures) admixed with sarcoma-like elements (background cells).