The bone tumor seen in children with characteristic lamellated periosteal reaction with a mottled appearance and extension into soft tissue is which of the folllowing?

Radiologically, Ewing's sarcoma is often associated with a lamellated or "onion peel" periosteal reaction. This appearance is caused by and splitting and thickening of the coex by tumor cells. The lesion is usually lytic and central. Endosteal scalloping is often present. The "onion-peel" appearance is often followed with a "moth-eaten" or mottled appearance and extension into soft tissue.