What is Ewing sarcoma?

➢ Very poorly differentiated malignant tumor that is included in the group of peripheral neuroectodermal tumors (neuroectoderm = embryonic nerve tissue) ➢ t (11; 22) causing the fusion of the EWS-FLI1 gene ➢ Tumor develops essentially in the medullary cavity of the diaphysis of the long bones and the pelvis ➢ Occurs during the 2 first decades with slight male predominance. ➢ The clinical manifestations of these bone locations can be: local pain / warmness/ edema. More rarely fever and leukocytosis mimicking an infection. Brown hemorragic and necrotic bone tumor rupturing the cortex Sheets of uniform small, round cells that are slightly larger and more cohesive than lymphocyte. They have scant cytoplasm, which may appear clear because it is rich in glycogen. The tumor cells do not produce bone or cartilage