[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. — 2004 ( NCI )]
UMLS (NCI) C1333514Extraosseous Ewing's Sarcoma/Peripheral Primitive Neuroectodermal Tumor