BCOR and sarcoma: BCOR positivity by immunohistochemistry is reported as a nonspecific finding shared across multiple sarcoma subtypes, and while initially thought to be a feature more unique to BCOR-rearranged sarcomas, its presence in a variety of tumors makes it a sensitive but nonspecific diagnostic finding (Pan et al. 2023; Astolfi et al. 2019; Antonescu et al. 2017).