BCOR immunostain is invariably positive in most BCOR-rearranged sarcomas, including the BCOR::CCNB3, BCOR::MAML3, BCOR-ITD sarcomas, and also in certain non-BCOR-rearranged sarcomas, such as YWHAE::NUTM2B sarcomas [31]. This evidence concerns the gene MAML3 and sarcoma.