BCOR and endometrioid stromal sarcoma: In addition to CCSK, this family also includes brain tumors, termed central nervous system BCOR-ITD (CNS BCOR-ITD); endometrial tumors, such as high-grade endometrial stromal sarcoma; and bone and soft tissue tumors, such as undifferentiated round cell sarcoma or primitive myxoid mesenchymal tumor of infancy [31, 32].