Soft tissue sarcoma is a rare cancer that starts in the soft tissues of the body, such as the fat, muscles, nerves, tendons, and blood and lymph vessels. Sarcomas can happen anywhere in the body, although close to half (about 40 percent) occur in the arms and legs.
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There are more than 70 types of soft tissue sarcoma or sarcoma-like growths. The risk and seriousness of each varies widely depending on the type, which is diagnosed according to where in the body the cancer started. Soft tissue sarcoma that arises in:
- smooth muscle is called leiomyosarcoma
- the gastrointestinal tract is called gastrointestinal stromal tumor
- fatty tissue (also called adipose tissue) is called liposarcoma
- the peripheral nervous system is called malignant schwannoma or malignant peripheral nerve sheath tumor
- blood vessels is called angiosarcoma, hemangioendothelioma, hemangiopericytoma, or solitary fibrous tumor
- connective tissue is called fibrosarcoma, dermatofibrosarcoma, low-grade fibromyxoid sarcoma or fibromatosis
Soft tissue sarcoma tumors can also affect more than one type of body tissue, or have no clear origin. This is the case for alveolar soft part sarcoma, clear cell sarcoma (malignant melanoma of soft parts), epithelioid sarcoma, synovial sarcoma, and undifferentiated soft tissue sarcoma.
But most of the time, there’s no clear reason why this cancer develops. Some types are more common for people of certain age groups, however. For example, rhabdomyosarcoma appears more often in children than in adults, and synovial sarcoma is more common in adolescents.
Unlike many cancers, soft tissue sarcoma often does not cause symptoms in the early stages, because it occurs in soft (usually elastic) tissue that is easily pushed out of the way by the growing tissue The first symptom you may notice is a painless lump. Sometimes, the tumor might cause pain, soreness, or difficulty breathing if it presses on nerves muscles, or blood vessels. Many people notice a sarcoma only after an unrelated injury draws attention to that part of the body.