Soft Tissue Sarcoma

Sarcomas are malignant (cancerous) tumors that develop in tissues which connect, support, or surround other structures and organs of the body. Muscles, tendons (bands of fiber that connect muscles to bones), fibrous tissues, fat, blood vessels, nerves, and synovial tissues are types of soft tissue. Soft tissue sarcomas are grouped together because they share certain microscopic characteristics, have similar symptoms, and are generally treated in similar ways. They are usually named for the type of tissue in which they begin. Examples of soft tissue sarcomas and the type of tissue in which they begin include the following:

Fibrous tissue (tissue that holds bones, muscles, and organs in place)—fibrosarcoma, malignant fibrous histiocytoma

Fatty tissue—liposarcoma

Skeletal muscle—rhabdomyosarcoma

Blood and lymph vessels—epithelioid hemangioendothelioma, angiosarcoma, lymphangiosarcoma, Kaposi sarcoma

Perivascular tissue (near or around blood vessels)—glomangiosarcoma, malignant hemangiopericytoma

Synovial tissue (tissue that lines joints, tendon sheaths, and fluid-filled sacs between tendons and bones)—synovial sarcoma

Peripheral nerves—malignant granular cell tumor, malignant peripheral nerve sheath tumor (also called malignant schwannoma or neurofibrosarcoma)

Mesenchymal cells (cells that develop into connective tissue, blood vessels, and lymphatic tissue)—gastrointestinal stromal tumor (GIST), malignant mesenchymoma

Other types of soft tissue sarcomas include alveolar soft part sarcoma, epithelioid sarcoma, desmoplastic small cell tumor, and clear cell sarcoma. At this time, scientists do not know the types of tissue in which these sarcomas begin. Many sarcomas have specific chromosomal alterations, which are used to help classify the tumors.

Soft tissue sarcomas can arise almost anywhere in the body. About 43 percent occur in the extremities (e.g., arms, legs); 34 percent occur in and around the internal organs (e.g., uterus, heart); 10 percent occur in the trunk (e.g., chest, back); and 13 percent occur in other locations. In very rare cases, these tumors develop in the gastrointestinal tract. A small percentage of these are GISTs. Malignant GISTs occur most commonly in the stomach and small intestine.

Symptoms

Soft tissue sarcomas usually appear as a lump or mass, but they rarely cause pain, swelling, or other symptoms. A lump or mass might not be a sarcoma; it could be benign (noncancerous), a different type of cancer, or another problem. It is important to see a doctor about any physical change, such as a lump or mass, because only a doctor can make a diagnosis.