We report an exceptional case of an undifferentiated round and spindle cell sarcoma, occurring in the periprostatic region of a 54-year-old male, with a 'high-grade endometrial stromal sarcoma-like' (HG-ESS) morphology and harboring a ZC3H7B::BCOR gene fusion identified by RNA-based next-generation sequencing. In this report, we describe the striking overlap of morphologic, immunohistochemical and molecular features of this current case and previously reported similar cases with ZC3H7B::BCOR fusion-positive HG-ESS, and discuss the differential diagnosis and possible pathogenesis of this unusual entity.