RT Journal Article SR Electronic T1 Highly Invasive and Metastatic High-grade Endometrial Stromal Sarcoma With BCOR Gene Alterations: A Case Report JF In Vivo JO In Vivo FD International Institute of Anticancer Research SP 1971 OP 1976 DO 10.21873/invivo.12920 VO 36 IS 4 A1 FENG LING A1 SIBEI RUAN A1 HUILING CHEN A1 XIAOMING XIONG A1 DONGMEI ZHAO A1 JOHANNES HAYBAECK A1 CUIWEI ZHANG YR 2022 UL http://iv.iiarjournals.org/content/36/4/1971.abstract AB Background: The coexistence of a uterine leiomyosarcoma and a high-grade endometrial stromal sarcoma (HGESS) is extremely rare, especially when one of the components causes metastasis. Case Report: A 46-year-old female with aggravated abdominal pain for more than 4 months was diagnosed with uterine malignant mesenchymal tumor composed of predominantly a leiomyosarcoma (99%) and a minor component of HGESS with BCL6 corepressor (BCOR) gene alterations (1%), with ovarian and pelvic metastases. Results: The volume of HGESS with BCOR gene alterations accounted for less than 1% of the tumor mass but caused ovarian and pelvic metastases. Conclusion: HGESS with BCOR gene alterations is extremely aggressive. We suggest that when both components of HGESS with BCOR gene alterations and uterine leiomyosarcoma are present in one patient, the HGESS with BCOR gene alterations needs to be highlighted in the pathological report, even if it accounts for less than 1% of the tumor volume.