GREB1 and undifferentiated (embryonal) sarcoma: This could indicate that molecular detection, including the GREB1 rearrangement, should be used with cases of HG-ESS, undifferentiated sarcoma, and other high-grade sarcomas, which cannot be classified as any specific uterine sarcoma subtype, to clarify whether they are poorly differentiated UTROSCT or a distinct sarcoma subtype.