Ewing Sarcoma Defined Ewing sarcoma is a cancerous bone tumor that affects children, adolescent and young adults—usually developing during puberty between the ages of 10 and 20 years old. Approximately 87% of Ewing sarcomas are in the long bone, meaning the arm, thigh, shin and pelvis. On rare occasion, Ewing sarcomas can occur in soft tissue like cartilage or nerves. These are called pPNET tumors and can be found in the nerve tissue in many parts of the body; if a pPNET is found in the chest,...