YAP1::KMT2A-rearranged sarcomas harbor a unique methylation profile and are distinct from sclerosing epithelioid fibrosarcoma and low-grade fibromyxoid sarcoma.

Sclerosing epithelioid fibrosarcoma (SEF) was originally described as a peculiar variant of fibrosarcoma in 1995. Subsequent studies showed that conventional SEF was associated with both immunohistochemical expression of MUC4 and EWSR1/FUS gene rearrangements with CREB3L1 as the predominant fusion partner. Since then, a distinct group of fibrous tumors characterized by YAP1::KMT2A and KMT2A::YAP1 gene rearrangements and SEF-like morphology has been described.

Reappraisal of soft tissue myoepithelial tumors by DNA methylation profiling reveals an epigenetically distinct group of mostly fusion-driven neoplasms.

Soft tissue myoepithelial tumors (METs) are diagnostically challenging tumors that require careful histologic and immunohistochemical characterization for accurate classification. Nearly half of METs show recurrent EWSR1 or FUS gene rearrangements with a diverse set of fusion partners. The diversity of fusion partners and lack of known driver abnormalities in many cases raises the question of whether METs represent a uniformly distinct tumor entity.

TFE3 -rearranged Head and Neck Neoplasms : Twenty-two Cases Spanning the Morphologic Continuum Between Alveolar Soft Part Sarcoma and PEComa and Highlighting Genotypic Diversity.

TFE3 rearrangements characterize histogenetically, topographically, and biologically diverse neoplasms. Besides being a universal defining feature in alveolar soft part sarcoma (ASPS) and clear cell stromal tumor of the lung, TFE3 fusions have been reported in subsets of renal cell carcinoma, perivascular epithelioid cell tumor (PEComa), epithelioid hemangioendothelioma and ossifying fibromyxoid tumors. TFE3 -related neoplasms are rare in the head and neck and may pose diagnostic challenges.