Definition of Ewing's sarcoma:

Ewing's sarcoma is a malignant (cancerous) bone tumor that affects children.

Causes, incidence, and risk factors:

Ewing's sarcoma can occur any time during childhood and young adulthood, but usually develops during puberty, when bones are growing rapidly. It is uncommon in African-American, African, and Chinese children.

The tumor may arise anywhere in the body, usually in the long bones of the arms and legs, the pelvis, or the chest. It may also develop in the skull or the flat bones of the trunk.

There are few symptoms. The most common is pain and occasionally swelling at the site of the tumor. Children may also break a bone at the site of the tumor after a seemingly minor injury (this is called a "pathologic fracture"). Fever may also be present.

The tumor often spreads (metastasis) to the lungs and other bones. Metastasis at the time of diagnosis is present in approximately one-third of children with Ewing's sarcoma. Rarely, Ewing's Sarcoma can occur in adults.