Source:http://linkedlifedata.com/resource/umls/id/C1333481
NCI: A spectrum of malignant tumors arising from the bone, 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