Sarcoma

Pediatric bone tumors are abnormal growths of tissue in the body, which form when abnormal cells multiply and grow. Bone tumors are abnormal tissue growths that start in the leg, ribs or arm bones. Tumors that start in the leg muscles, tendons, fat or blood vessels are referred to as soft tissue tumors. Malignant bone and soft tissue tumors are called sarcomas.

Types of pediatric bone cancers

The two main types of bone cancers that develop in children are osteosarcoma and Ewing sarcoma. Primary bone cancer is cancer that starts in the bone tissue. Secondary, or metastatic bone cancer, is when cancer spreads to the bone from another site in the body.

Other types of bone cancer include:

• Chondrosarcoma — cancer of the cartilage
• Chordoma — a primary bone tumor that usually occurs in the skull or the spine
• Ewing sarcoma — tumors that typically develop in the cavity of the leg and arm bones
• Fibrosarcoma and malignant fibrous histiocytoma — cancers that develop in soft tissues, such as tendons, ligaments, fat and muscle, and then move to the leg, arm or jaw bones
• Giant cell tumor — a malignant primary bone tumor. Giant cell tumors are most commonly found in the arm or leg bones

While some adult cancers are linked to environmental or lifestyle factors, childhood cancers can develop due to DNA changes in cells early in a child's life, or even before birth. The development of Ewing sarcoma is most often the result of a chromosome rearrangement between chromosomes 11 and 22. Some physicians classify Ewing sarcoma as a primitive neuroectodermal tumor (PNET), which means that the tumor may have started in fetal or embryonic tissue and developed into nerve tissue.

Osteosarcoma (or osteogenic sarcoma) typically occurs in long bones, such as the humerus arm bone, the femur and tibia in the legs or the pelvis. Osteosarcoma is most commonly found in children and young adults between the ages of 10 and 25. Osteosarcoma is also more common in boys than in girls and can spread to other areas of the body, such as the lungs.

The direct cause of Osteosarcoma is unclear. Doctors and scientists have determined that osteosarcoma is linked to other medical conditions. Inherited DNA mutations may also be a factor.

According to the American Cancer Society, bone cancers account for about 3 percent of childhood cancers. It's important to know that all cancers in children are considered rare, so the chances of developing bone cancer in childhood are also rare.

Bone cancers are more commonly found in older children and teenagers. Ewing sarcoma typically develops in children and young adults ages five to 20 years old. Ewing sarcoma is most often found in young teens and tends to start in the pelvic or hip bones, the ribs or shoulder blades or the longer leg bones. Osteosarcoma tends to develop in areas where the bone is growing quickly, such as the leg or arm bones.

Most osteosarcomas are found at an early stage before cancer has spread to other parts of the body. It's not uncommon for bone cancers in children to be first diagnosed as something else. An active child who plays a lot of sports may have bumps or bruises on their legs or arms, but a doctor won't know that there's a potential tumor in the bone until symptoms get worse, or the bone tumor appears in an X-ray.