Ewing's Sarcoma
Ewing sarcoma is the second most common highly malignant primary bone tumour of childhood after osteosarcoma, typically arising from medullary cavity with invasion of Haversian system. They usually present as moth-eaten destructive permeative lucent lesions in the shaft of long bones with large soft tissue component without osteoid matrix, and typical onion skin periostitis. It may also involve flat bones and appears sclerotic in up to 30% of cases.