Endometrial carcinosarcoma IIB refers to stage II in the surgical pathological staging of endometrial carcinosarcoma, i.e., the tumor invades the interstitium of the uterine cervix without extrauterine spread. 1. Endometrial carcinosarcoma sarcoma: it is one of the pathological types of endometrial carcinoma, which is clinically rare and common in postmenopausal women. It is a kind of uterine malignant tumor composed of a mixture of malignant epithelial and malignant mesenchymal components, and is also known as malignant mixed tumors of Millerian ducts, whose staging performs the new staging of endometrial carcinoma in 2009. 2. Pathological staging of endometrial cancer sarcoma: In 1988, surgical pathological staging divided stage II into IIA and IIB, of which IIA is the involvement of mucosal glands of the cervical canal, and IIB is the involvement of cervical mesenchyme, and the new staging promulgated by the International Federation of Gynecology and Obstetrics in 2009 modified stage II, and the tumor is no longer classified as stage II when it involves the cervical endocervical glands. Therefore, endometrial cancer sarcoma IIB refers to stage II in the surgical pathologic staging of endometrial cancer, which is used to indicate the development of endometrial cancer sarcoma and the severity of the lesion.