PDGFRB and endometrioid stromal sarcoma: With the expanded use of molecular techniques, it has become evident that some tumors previously classified as STUMP belong to distinct non-smooth muscle neoplasm categories, such as high-grade endometrial stromal sarcoma (HG-ESS) with BCOR alterations, uterine sarcomas with NTRK rearrangements or COL1A::PDGFRB fusions, and IMTs [3].