extraskeletal Ewing sarcoma/peripheral primitive neuroectodermal tumor (MONDO_0021039) is a spectrum of malignant tumors arising from the soft tissues, characterized morphologically by the presence of small round cells. Ewing sarcoma and peripheral primitive neuroectodermal tumor represent the ends of a spectrum, with Ewing sarcoma lacking evidence of neural differentiation and the markers that characterize the peripheral primitive neuroectodermal tumor. Ewing sarcoma and peripheral primitive neuroectodermal tumor may share cytogenetic abnormalities, proto-oncogene expression, cell culture and immunohistochemical abnormalities. Pain and the presence of a mass are the most common clinical symptoms. Also known as: extraosseous Ewing sarcoma/peripheral primitive neuroectodermal tumor, extraosseous Ewing sarcoma/peripheral primitive neuroectodermal tumour, extraosseous Ewing's sarcoma/peripheral primitive neuroectodermal tumor, extraosseous Ewing's sarcoma/peripheral primitive neuroectodermal tumour, extraosseous Ewings sarcoma-primitive neuroepithelial tumor, extraosseous Ewings sarcoma-primitive neuroepithelial tumour.