Soft tissue sarcoma types are determined by the way a sample of cells from the tumor looks under a microscope. A surgeon will obtain the sample during a biopsy or during surgery to remove the tumor.
There are more than 80 types of soft tissue sarcoma or sarcomalike growths. Knowing which type you have helps doctors predict how the tumor will respond to specific treatments. It also allows them to personalize your treatment.
Soft tissue sarcoma is usually classified based on where in the body the cancer started:
- If sarcoma starts in smooth muscle, it is called leiomyosarcoma.
- Gastrointestinal tract sarcoma is called a gastrointestinal stromal tumor.
- Soft tissue sarcoma in fatty tissue (also called adipose tissue) is called liposarcoma.
- Malignant schwannoma or malignant peripheral nerve sheath tumors start in the peripheral nervous system.
- Soft tissue sarcoma starting in the blood vessels can be angiosarcoma, hemangioendothelioma, hemangiopericytoma, or a solitary fibrous tumor.
- Fibrosarcoma, dermatofibrosarcoma, low-grade fibromyxoid sarcoma, and fibromatosis are sarcomas of the connective tissue.
Soft tissue sarcoma tumors can affect more than one type of body tissue. They also may 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.
Here is a brief overview of the most commonly diagnosed forms of soft tissue sarcoma in adults. There are also a number of soft tissue sarcomas that are more common in children and young adults. These include rhabdomyosarcoma, Ewing sarcoma, and desmoplastic round cell tumors.
- Gastrointestinal stromal tumor (GIST): GISTs begin in the gastrointestinal tract, usually in the stomach. These tumors tend to be large in size and can spread to other parts of the body. Learn more about GISTs.
- Liposarcoma: Tumors that begin in fatty tissue are known as liposarcoma. There are several different forms of liposarcoma. Some are much more aggressive than others so it’s important to know the subtype. Learn more about liposarcoma.
- Leiomyosarcoma: These tumors begin in the smooth muscle tissue that lines hollow organs. The uterus is the most common location among women. Leiomyosarcoma can also begin in organs such as the bladder and stomach. Learn more about leiomyosarcoma. Find in-depth information on leiomyosarcoma of the uterus in our patient guide to uterine sarcoma.
- Undifferentiated pleomorphic sarcoma (UPS): UPS can occur anywhere in the body. It usually occurs in the back of the abdomen, in the arms, or in the legs, especially the thighs. These tumors often grow quickly and can spread to other parts of the body, including the lungs. Other names for UPS include malignant fibrous histiocytoma and myxofibrosarcoma.
- Synovial sarcoma: Synovial sarcoma typically occurs in the arms, legs, fingers, and toes. It is more common in children and young adults. The most common sign is a painful lump. Newer therapies such as immunotherapy and epigenetic therapy show great potential for treating these tumors. Learn more about synovial sarcoma.
- Malignant peripheral nerve sheath tumor (MPNST): MPNSTs are rare, highly aggressive tumors that start in the nerve cells. The most common sign is a painful lump. About one-third of MPNSTs are linked to the genetic condition neurofibromatosis.
- Desmoid tumor: Desmoids are related to soft tissue sarcoma, but they are not a cancer because they do not spread to other parts of the body. Some desmoids can be monitored and don’t need other treatment. Others, however, can be aggressive. Learn more about desmoid tumors.
- Solitary fibrous tumor and hemangiopericytoma: Solitary fibrous tumors and hemangiopericytomas can form anywhere in the body. Some are benign (not cancerous), while others may be highly aggressive. Most often, these tumors grow slowly over many years. Most are not found until they are very large.
- Fibrosarcoma: Fibrosarcoma was once thought to be one of the most common forms of soft tissue sarcoma. Thanks to advances in diagnostic techniques, fibrosarcoma is now considered a rare form of the disease.
- Vascular sarcoma: Vascular tumors start in the blood vessels. They range from benign hemangiomas and low-grade epitheloid hemangioendotheliomas to highly aggressive angiosarcomas. Learn more about angiosarcomas.
- Epithelioid sarcoma: These tumors are more common in young adults. The classic form of the disease grows slowly and occurs in the feet, arms, legs, or forearms of younger men. Epithelioid tumors can also begin in the groin, and these tumors tend to be more aggressive.
- Alveolar soft part sarcoma (ASPS): ASPS is an extremely rare sarcoma that typically starts in the lower extremities of people between the ages of 15 and 40. It is a slow-growing tumor but one that often spreads to other parts of the body, such as the lungs and brain.
- Clear cell sarcoma and melanoma of soft parts: This tumor has features of both soft tissue sarcoma and melanoma (an aggressive form of skin cancer). However, since it starts in the soft tissue and usually does not affect the skin, it is typically classified as sarcoma. The foot and ankle are common locations.
- Extraskeletal myxoid chondrosarcoma (EMC): EMC tumors are painless masses that are soft and gelatinous in consistency. They tend to grow slowly and spread to other parts of the body, particularly the lungs. These tumors typically affect people between the ages of 30 and 60 and most commonly occur in the lower extremities.
There are a number of sarcomalike growths that are typically benign (not cancerous), though in some cases, they can spread to other parts of the body. These include:
- ossifying fibromyxoid tumor
- perivascular epitheloid cell tumor, lymphangioleiomyomatosis, angiomyolipoma, and sugar cell tumor
- giant cell tumor of tendon sheath and pigmented villonodular synovitis
- myoepithelial tumors of soft tissue
- glomus tissue tumor
The least aggressive growths are these benign tumors:
- granular cell tumors