A Novel EPC1::KDM2B Fusion in High-grade Endometrial Stromal Sarcoma

Katherine M Vroobel; Sana Khalid; Silvia Cavalchini; Ayoma D Attygalle

doi:10.1097/PGP.0000000000001026

A Novel EPC1::KDM2B Fusion in High-grade Endometrial Stromal Sarcoma

Int J Gynecol Pathol. 2024 Mar 11. doi: 10.1097/PGP.0000000000001026. Online ahead of print.

Authors

Katherine M Vroobel¹, Sana Khalid¹, Silvia Cavalchini², Ayoma D Attygalle¹

Affiliations

¹ Department of Cellular Pathology, The Royal Marsden NHS Foundation Trust, London (K.M.V., S.K., A.D.A.).
² Clinical Genomic Department, The Royal Marsden NHS Foundation Trust, Sutton (S.C.), UK.

PMID: 38501593
DOI: 10.1097/PGP.0000000000001026

Abstract

The spectrum of endometrial stromal sarcoma (ESS) has expanded substantially since the publication of the most recent World Health Organisation (WHO) Classification of Female Genital Tumours and the advent of widely available genomic testing. We describe a uterine mesenchymal tumor harboring a novel EPC1::KDM2B fusion, best classified within the umbrella of high-grade endometrial stromal sarcoma (HGESS). This tumor was composed of a uniform population of spindled cells with some myxoid stroma, a mitotic rate of up to 21/10 high-power fields, and a largely pushing margin with focal vascular invasion. Immunohistochemistry showed strong and diffuse cyclin D1 positivity while CD10, WT1, DOG1, CD117, CD34, CD99, S100, MelanA, SMA, desmin, and h-caldesmon were negative. The tumor was confined to the uterus and no recurrence has been detected thus far, albeit with a short follow-up interval of 9 mo.