We report a case of high-grade endometrial stromal sarcoma originally assumed to be a benign leiomyoma. with BCOR internal tandem duplicates resulting in BCOR overexpression. A 34-year-old female presented to the gynecologic oncology service for recent miscarriage attributed to a large leiomyoma. She reported symptoms of vaginal bleeding and abdominal pain. https://www.roneverhart.com/RKT-9-RDO/