Myoepithelial neoplasms represent a heterogenous group of tumors of which classification is incomplete and evolving. Those of the soft tissues often form genetically distinct subgroups that differ from those arising within salivary glands. Soft-tissue myoepithelial tumors (including mixed tumors that show true glandular or ductal differentiation) exhibit a spectrum of different morphologic patterns, making them difficult to distinguish from a variety of other neoplasms. They have been increasingly shown to harbor genetic fusions involving EWSR1 and partner genes that are not seen in the well-characterized tumor classes involving EWSR1 translocations. We review the spectrum of soft-tissue myoepithelial tumors, discussing recent immunohistochemical and genetic findings and the differential diagnosis.
Sarcoma Unit, Royal Marsden Hospital, London, UK
Supported by the NIHR RM/ICR Biomedical Research Centre.
The authors have no conflicts of interest to disclose.
Reprints: Khin Thway, MBBS, BSc, FRCPath, Department of Histopathology, The Royal Marsden NHS Foundation Trust, 203 Fulham Road, London SW3 6JJ, UK (e-mail: firstname.lastname@example.org).