Ewing Sarcoma

Ewing sarcoma is the second most common form of bone tumour in children, and third after myeloma and osteosarcoma overall.


The lesion may present in any bone, or even outside bone (peripheral neuroectodermal tumour). The most commonly affected bone is the femur, either at the diaphysis or metaphysis. Other long bones of the appendicular skeleton, as well as the pelvis and ribs, are often involved.
Macroscopically, the tumour is tan-grey and locally destructive. On imaging, the characteristic appearance is of a lytic lesion with periosteal reaction surrounding the extraosseus extension; this gives the classical 'onion-skin' appearance.
Microscopically, the tumour is formed by small round blue cells. There is minimal cytoplasm, fine chromatin, with indistinct cell borders. Rosettes may form. There is often necrosis and haemorrhage.
Immunohistochemistry is positive for CD99, vimentin and neuron-specific enolase.
The characteristic translocation of t(11;22), merging the EWS and FLI1 genes and forming a hybrid, oncogenic transcription factor.



Local Therapy

The main choice is surgery, radiotherapy or both.

  • Surgery has better outcomes in trials, but this is likely at least in part due to selection bias (i.e. surgery is used for smaller lesions in better locations)
  • Radiotherapy is typically used for difficult surgical sites, such as the spine or pelvis
  • Surgery may be followed by radiotherapy in cases where there are positive margins

The typical radiotherapy dose is 50.4 Gy in 28 fractions (most sites) or 45 Gy in 25 fractions (where spinal cord toxicity is problematic). The GTV->CTV margin is 2 cm. The exact technique is site dependent.

Systemic Therapy

This is an essential component of treatment as about 90% of patients relapse without chemotherapy.
The most well established therapy is alternating:

  • Vincristine, doxorubicin and cyclophosphamide
  • Ifosfomide and etoposide

Chemotherapy generally starts first


Survival is better for:

  • Children under 10 (85% versus 50%)
  • Appendicular versus axial site (60% versus 40%)