What Is Sarcoma?

Sarcoma is a rare cancer of the connective tissues that hold the body together, including the muscles, tendons, blood vessels, fat, nerves, deep skin tissue, bones and cartilage. There are about 14,000 new cases of sarcoma diagnosed in the United States every year, and it makes up about 15 percent of the cancer diagnoses in children under age 20. Sarcoma is generally divided into two main categories, osteosarcoma and soft tissue sarcoma.


Osteosarcoma, or bone sarcoma, is a malignant tumor of the bone. Unlike cancer that starts elsewhere and spreads to the bones, osteosarcoma generally starts in the cells that grow into new bone tissue, most often in the ends of the long bones of the body, such as the arms and legs. In children and teenagers, osteosarcoma often develops near the knee.

Ewing sarcoma is a particular type of bone cancer that affects mostly children and young adults. About 200 new cases are diagnosed in children and adolescents in the United States each year, and only 20 diagnosed in adults. It produces tumors that grow in the long bones of the arms and legs, as well as the flat bones of the chest, pelvis, back or head.

Soft tissue sarcoma

Soft tissue sarcoma is a rare cancer that occurs in all segments of the United States population. It can occur in the muscles, fat, blood vessels, tendons, fibrous tissues and synovial tissues (tissues around joints), but about 40 percent of new cases occur in the legs at or above the knee. Other possible locations include the torso, the area around the head and neck and in the abdominal cavity. From there, soft tissue sarcomas can invade surrounding tissue and can spread (metastasize) to other organs of the body, forming secondary tumors.

Types of soft tissue sarcoma include:

  • Spindle cell sarcoma
  • Liposarcoma
  • Fibrosarcoma
  • Dermatofibrosarcoma protuberans
  • Malignant fibrous histiocytoma (MFH)
  • Synovial cell sarcoma
  • Epithelioid sarcoma
  • Rhabdomyosarcoma
  • Leiomyosarcoma
  • Malignant peripheral nerve sheath tumor, also called neurofibrosarcoma or malignant schwannoma
  • Gastrointestinal stromal tumors, also called GIST
  • Extraosseous tumor
  • Vascular sarcoma
  • Alveolar soft-parts sarcoma
  • Kaposi sarcoma

Remember, there are many types of lumps in the soft tissues of the body, and most of them are not cancerous. Noncancerous lumps include fatty tumors called lipomas, fluid-filled cysts and collections of abnormal blood vessels, called hemangiomas. Your physician can determine if lumps are cancerous or non cancerous.