Background:The uterine leiomyosarcoma combined high-grade endometrial stromal sarcoma (ESS) is quite rare.Case presentation: We reported such a case in which high-grade ESS with BCOR gene alterations and leiomyosarcoma coexist in a patient. And, most impressively, high-grade ESS with BCOR gene alterations caused ovarian and pelvic metastases, although its volume was less than 1% of leiomyosarcoma.Conclusions: We suggested that when both high-grade ESS BCOR gene alterations and leiomyosarcoma are present in a patient, the high-grade ESS needs to be noted in the pathological report even if it accounts for less than 1% of the tumour mass.
