<prompt> Ewings sarcoma is associated withCD-56CD-38CD-117CD-139  <response>: A CD-56 Tumor cells in Ewings sarcoma show diffuse membrane positivity for CD-56. Tumor cells are also positive for neuron-specific enolase. Ewings sarcoma or Endothelial sarcoma of bone: It is a highly malignant tumour, occurring between the age of 10-20 years. Multicentric in origin. Cytogenetic abnormalities associated with Ewings sarcoma is the reciprocal translocation of the long arm of chromosomes 11 and 22 It arise in the diaphysis of long bone Subperiosteal bone formation Histopathologically -- Pseudo rosette formation. The tumour grow fast and metastasises through the blood stream to the lungs and to other bones. Clinical Features -- Pain, swelling and Fever, so it may be confused with osteomyelitis X-Ray show - Onion peel appearance Treatment - Highly radio sensitive tumour, so Radiotherapy is highly effective for control of the local tumour and chemotherapy for control of the metastasis. 