Likewise, YWHAE-rearranged high-grade ESS represents a molecularly distinct category separate from LG-ESS despite some histologic overlap [63,66]; and NTRK-rearranged uterine spindle cell sarcomas form a fusion-defined group with a characteristic immunophenotype and a clear therapeutic target not apparent on routine histology [108,113]. This evidence concerns the gene YWHAE and endometrioid stromal sarcoma.