The Ewing family of tumors is a group of cancers that start in the bones or nearby soft tissue that share some common features. They can occur at any age, but these tumors are most common in early teenage years. There are 3 main types of Ewing tumors:

• Ewing sarcoma of bone
• extraosseous Ewing tumor (EOE)
• peripheral primitive neuroectodermal tumor (PPNET)

Ewing sarcoma of bone

Ewing sarcoma, the most common of the tumors in this family, is a type of bone tumor that occurs most often in children. It was first described by Dr. James Ewing in 1921, who found it was different from the more common bone tumor, osteosarcoma. It is more likely to respond to radiation, and its cells look different when viewed under a microscope.

Extraosseous Ewing tumor

Extraosseous Ewing (EOE) tumors start in soft tissues around bones, but they look and act very much like Ewing sarcomas in bones. They are also known as extraskeletal Ewing sarcomas.

Peripheral primitive neuroectodermal tumor

This rare childhood cancer also starts in the bone or soft tissue and shares many features with Ewing tumor and EOE. Peripheral PNETs that start in the chest wall are known as Askin tumors.

(Peripheral PNETs are similar to, but not quite the same as, PNETs of the brain and spinal cord. For more information on those tumors, see the separate American Cancer Society document, Brain and Spinal Cord Tumors in Children.)

Researchers have found that the cells that make up Ewing sarcoma, EOE, and PPNET are very similar. They have the same DNA abnormalities and share similar proteins, which are rarely found in other types of cancers. Because of this, it is believed that these 3 cancers develop from the same type of normal cells in the body. Although there are slight differences among these tumors, they are all treated in the same way.

Most Ewing tumors occur in the bones. The most common sites are the pelvis, the chest wall (such as the ribs or shoulder blades), and the legs, mainly in the middle of the long bones. (In contrast, osteosarcoma usually occurs at the ends of the long bones, especially around the knees.) Extraosseous Ewing tumors can occur almost anywhere.

Last Medical Review: 08/20/2009
Last Revised: 08/20/2009