label: Extraskeletal Ewing Sarcoma/Peripheral Primitive Neuroectodermal Tumor
label_lc: extraskeletal ewing sarcoma/peripheral primitive neuroectodermal tumor
description: 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.