Sarcoma

Sarcomas are cancers that can arise from bones or soft tissues (such as muscles, fat tissues, or tendons) in the body. There are many types of sarcomas, based on where they start in the body and how they appear under a microscope. Sarcomas can grow directly into nearby organs or tissues, or can spread (metastasize) through the bloodstream to other parts of the body, particularly the lungs. The type of sarcoma that develops often depends on the age of the child. For example, bone sarcomas occur more commonly in teenagers than in younger children, whereas certain soft tissue sarcomas are seen more commonly in younger children. Less than 15% of childhood cancer diagnoses are sarcomas.

Pediatric Bone Sarcoma

Osteosarcoma. The most common type of bone cancer in children, teenagers, and young adults is osteosarcoma, which often develops in the cells that form bone, known as osteoblasts. The majority of osteosarcoma tumors are located in an area where bones are growing quickly during childhood — in the growth plate near the growing end of a bone (called the metaphysis). Although osteosarcoma tumors can occur in any bone of the body, they develop most commonly just above and just below the knee.

Ewing sarcoma. Ewing sarcoma is another type of pediatric sarcoma that typically starts in the bone. Ewing sarcoma can arise from any bone in the body, although it can sometimes arise from soft tissues or other organs. Compared to osteosarcoma, Ewing sarcoma is more likely to start in the bones of the chest wall (such as the ribs or shoulder blade), the hip (pelvis), or spine.

Pediatric Soft Tissue Sarcoma

In soft tissue sarcomas, cancer cells form in the soft tissues of the body, such as fat, muscles, tendons, blood and lymph vessels, nerves, deep skin tissues, and tissues around joints (known as synovial tissues). Rhabdomyosarcoma is a type of soft tissue sarcoma that makes up about half of all cases of pediatric soft tissue sarcoma. Rhabdomyosarcoma usually arises from skeletal muscle and is most commonly diagnosed in children under the age of 10 years.