Soft tissue sarcomas are a group of rare cancers that affects the soft tissues of the body, such as fat, muscles, nerves, tendons, and blood and lymph vessels. These tissues connect, support, and surround other parts of the body. Sarcomas can occur in any location in the body, although about 40 percent occur in the arms and legs.
There are more than 70 different subtypes of soft tissue sarcomas and sarcoma-like growths. They are identified by their tissue of origin, and include tumors of smooth muscle (leiomyosarcoma), the gastrointestinal tract (gastrointestinal stromal tumors, or GIST), adipose tissue (liposarcoma), and peripheral nervous system (malignant schwannoma or malignant peripheral nerve sheath tumor).
Soft tissue sarcomas also include:
Tumors of Vascular Structures
- Hemangiopericytoma (Solitary Fibrous Tumor)
Tumors of Fibrous Tissue
- Fibromatoses (desmoid tumors)
- Low-grade fibromyxoid sarcoma
Tumors of more than one tissue type
- Malignant mesenchymoma
- Malignant triton tumor
Tumors of Unknown Origin
- Alveolar soft part sarcoma (ASPS)
- Clear cell sarcoma (malignant melanoma of soft parts)
- Epithelioid sarcoma
- Synovial sarcoma
- Undifferentiated soft tissue sarcoma
Because there are many subtypes of soft tissue sarcoma, each with different characteristics, the risk and seriousness of the disease can vary widely. In some patients, sarcomas are minor, nonthreatening tumors that can be cured with surgery. In others, the tumors can be large and much more aggressive, requiring chemotherapy and radiation therapy as well as surgery.
The curability of a particular sarcoma depends in part on finding it early and treating it promptly.
Most soft tissue sarcomas do not have any identifiable risk factors. However, some subtypes of sarcoma are more common in specific age groups — for example, rhabdomyosarcoma is more common in children than in adults, and synovial sarcomas are more common in adolescents.
Some familial syndromes can predispose people to sarcoma, including neurofibromatosis, Gardner’s syndrome, Li-Fraumeni syndrome, and retinoblastoma.
Soft tissue sarcomas often do not cause symptoms in the early stages, and there is not yet a routine screening test available to detect these tumors. The first noticeable symptom usually is a painless lump. Eventually, the tumor might cause some pain or soreness as it impinges on nerves and muscles. In many cases, an injury unrelated to the cancer draws attention to the presence of the sarcoma.