neuroectodermal tumor Ewings sarcoma A malignant tumor of the bone which always arises in the medullary tissue, occurring more often in cylindrical bones. There are conspicuous foci of necrosis in association with irregular masses of small, regular, rounded or ovoid cells with very scanty cytoplasm. The tumor occurs usually before the age of 20, about twice as frequently in males as in females. (From Dorland, 27th ed; Stedman, 25th ed) A small round cell tumor that lacks morphologic, immunohistochemical, and electron microscopic evidence of neuroectodermal differentiation. It represents one of the two ends of the spectrum called Ewing's sarcoma/peripheral neuroectodermal tumor. It affects mostly males under age 20, and it can occur in soft tissue or bone. Pain and the presence of a mass are the most common clinical symptoms. A spectrum of malignant tumors, affecting mostly males under age 20, 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. These tumors may occur in the soft tissues or the bones. Pain and the presence of a mass are the most common clinical symptoms. DOID:3369 ES Ewing Family of Tumors Ewing Sarcoma/Peripheral Primitive Neuroectodermal Tumor Ewing Tumor Ewing sarcoma Ewing's Family of Tumors Ewing's Family of Tumours Ewing's Sarcoma/Peripheral Primitive Neuroectodermal Tumor Ewing's sarcoma Ewing's sarcoma (morphologic abnormality) Ewing's tumour Ewings Tumor GeneRIF:11313995 GeneRIF:11956622 GeneRIF:11992404 GeneRIF:12054564 GeneRIF:12172985 GeneRIF:12447693 GeneRIF:12527902 GeneRIF:12557222 GeneRIF:12700668 GeneRIF:14528100 GeneRIF:14977835 GeneRIF:15044653 GeneRIF:15077162 GeneRIF:15273724 GeneRIF:15282325 GeneRIF:15310753 GeneRIF:15328192 GeneRIF:15581626 GeneRIF:15748890 GeneRIF:15919668 James Malone MSH:D012512 NCIt:C27291 NCIt:C4817 SNOMEDCT:76909002 Tomasz Adamusiak Tumors of the Ewing's Family URI: http://www.ebi.ac.uk/cellline#Ewing_sarcoma osteosarcoma