Original Article

ZC3H7B-BCOR high-grade endometrial stromal sarcomas: a report of 17 cases of a newly defined entity

Published online:


High-grade endometrial stromal sarcoma likely encompasses underrecognized tumors harboring genetic abnormalities besides YWHAE–NUTM2 fusion. Triggered by three initial endometrial stromal sarcomas with ZC3H7B–BCOR fusion characterized by high-grade morphology and aggressive clinical behavior, we herein investigate the clinicopathologic features of this genetic subset by expanding the analysis to 17 such tumors. All of them occurred in adult women with a median age of 54 (range, 28–71) years. They were predominantly based in the endomyometrium and demonstrated tongue-like and/or pushing myometrial invasion. Most were uniformly cellular and displayed haphazard fascicles of spindle cells with mild to moderate nuclear atypia. Myxoid matrix was seen in 14 of 17 (82%) tumors, and collagen plaques were seen in 8 (47%). The mitotic index was ≥10 mitotic figures/10 high-power fields (HPFs) in 14 of 17 (82%) tumors with a median of 14.5 mitotic figures/10 HPFs. No foci of conventional or variant low-grade endometrial stromal sarcoma were seen. All tumors expressed CD10 with only limited or absent desmin, SMA and/or h-caldesmon staining. ER and PR expression in >5% of cells was seen in 4 of 12 (33%) tumors. Diffuse cyclin D1 and BCOR immunoreactivity was present in 7 of 8 (88%) and 7 of 14 (50%) tumors, respectively. Fluorescence in situ hybridization or targeted RNA sequencing confirmed ZC3H7B–BCOR fusion in all tumors, including four and two previously diagnosed as myxoid leiomyosarcoma and undifferentiated uterine sarcoma, respectively. Limited clinical data suggest that patients present at higher stage and have worse prognosis compared with published outcomes in low-grade endometrial stromal sarcoma. Tumors with ZC3H7B–BCOR fusion constitute a distinct group of endometrial stromal sarcomas with high-grade morphology that should be distinguished from other uterine mesenchymal neoplasms that may demonstrate myxoid morphology.

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Author information


  1. Department of Pathology, Memorial Sloan Kettering Cancer Center, New York, NY, USA

    • Natasha Lewis
    • , Robert A Soslow
    • , Deborah F Delair
    • , Kay J Park
    • , Rajmohan Murali
    • , Travis J Hollmann
    • , Javier A Arias-Stella III
    • , Meera Hameed
    • , Ryma Benayed
    • , Marc Ladanyi
    • , Denise Frosina
    • , Achim A Jungbluth
    • , Cristina R Antonescu
    •  & Sarah Chiang
  2. Department of Pathology, The Norwegian Radium Hospital, Oslo University Hospital, Oslo, Norway

    • Ben Davidson
  3. Faculty of Medicine, University of Oslo, Oslo, Norway

    • Ben Davidson
  4. Section for Cancer Cytogenetics, Institute of Cancer Genetics and Informatics, The Norwegian Radium Hospital, Oslo University Hospital, Oslo, Norway

    • Francesca Micci
    •  & Ioannis Panagopoulos
  5. Department of Pathology, Vancouver General Hospital, Vancouver, BC, Canada

    • Lien N Hoang
  6. Department of Pathology, Massachusetts General Hospital, Boston, MA, USA

    • Esther Oliva
    •  & Robert H Young
  7. Department of Pathology, Harvard Medical School, Boston, MA, USA

    • Esther Oliva
    •  & Robert H Young
  8. Gynecologic Medical Oncology Service, Department of Medicine, Memorial Sloan Kettering Cancer Center, New York, NY, USA

    • Martee L Hensley
  9. Gynecology Service, Department of Surgery, Memorial Sloan Kettering Cancer Center, New York, NY, USA

    • Mario M Leitao Jr


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Competing interests

The authors declare no conflict of interest.

Corresponding author

Correspondence to Sarah Chiang.