Ewing sarcoma/peripheral primitive neuroectodermal tumor of bone (MONDO_0021123, a Monarch Disease Ontology identifier) is a spectrum of malignant tumors arising from the bone and 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: Ewing's sarcoma/peripheral primitive neuroectodermal tumor of bone, Ewing's sarcoma/peripheral primitive neuroectodermal tumour of bone, bone tissue Ewing sarcoma/peripheral primitive neuroectodermal tumor, bone tissue Ewing sarcoma/peripheral primitive neuroectodermal tumour.