Uterine mesenchymal tumours: recent advances

Almost all uterine mesenchymal tumours have been historically classified as either smooth muscle or endometrial stromal neoplasms. Recent application of molecular techniques has identified numerous lesions with distinctive genetic abnormalities and clinicopathological characteristics. Newly discovered uterine sarcoma subtypes include high-grade endometrial stromal sarcomas withBCORgenetic abnormalities, fibrosarcoma-like uterine sarcomas withNTRKrearrangements andCOL1A-PDGFRBfusions, as well as undifferentiated uterine sarcomas withSMARCA4mutations. NovelPLAG1andPGRfusions have been identified in subsets of myxoid and epithelioid leiomyosarcomas. Some uterine tumours resembling ovarian sex-cord tumour harbourGREB1andESR1rearrangements. Histological and immunophenotypical features as well as underlying genetic abnormalities defining these lesions are discussed.