Source: The American Cancer Society

What is a soft tissue sarcoma?

A sarcoma is a type of cancer that develops from certain tissues, like bone or muscle. There are 2 main types of sarcoma: bone sarcomas and soft tissue sarcomas. Soft tissue sarcomas can develop from soft tissues like fat, muscle, nerves, fibrous tissues, blood vessels, or deep skin tissues. They can be found in any part of the body. Most of them develop in the arms or legs. They can also be found in the trunk, head and neck area, internal organs, and the area in back of the abdominal cavity (known as the retroperitoneum). Sarcomas are not common tumors, and most cancers are the type of tumors called carcinomas.

There are many types of soft tissue tumors, and not all of them are cancerous. When a tumor is not cancerous, it is called benign. When the term sarcoma is part of the name of a disease, it means the tumor is malignant (cancer). There are about 50 different types of soft tissue sarcomas (not all are listed here).

This document is about soft tissue sarcomas in adults. Sarcomas occurring in bone, such as osteosarcomas and Ewing tumors are discussed in separate documents. Rhabdomyosarcoma, the most common type of soft tissue sarcoma seen in children, is also discussed in another document.

Fat tissue tumors

Benign fat tissue tumors

Lipomas are benign tumors of fat tissue. They are the most common benign soft tissue tumor. Most are found just under the skin, but they can develop anywhere in the body.

Lipoblastomas are benign fat tumors that occur in infants and young children.

Hibernomas, like lipomas, are also benign fat tissue tumors. They are much less common than lipomas.


Cancerous fat tissue tumors

Liposarcomas are malignant tumors of fat tissue. They can develop anywhere in the body, but they most often develop in the thigh, behind the knee, and inside the back of the abdomen. They occur mostly in adults between 50 and 65 years old.


Muscle tissue tumors

There are 2 types of muscle: smooth and skeletal.

Smooth muscle is found in internal organs such as stomach, intestines, blood vessels, or uterus (womb) and causes them to contract. These muscles are involuntary — we don’t control their movement.

Skeletal muscle is sometimes called striated (because stripes can be seen inside the cells under the microscope). This is the type of muscle that lets us move our arms and legs and other body parts when we want them to move— this is called voluntary movement.


Benign muscle tumors

Leiomyomas are benign tumors of smooth muscle (or involuntary muscle). Leiomyomas can start from the walls of blood vessels, so they can develop almost anywhere in the body. They can be found in both men and women, but the most common place to find a leiomyoma is in the walls of the uterus. They are often called fibroids.

Rhabdomyomas are rare benign tumors of skeletal muscle.


Malignant muscle tumors

Leiomyosarcomas are malignant tumors of smooth muscle. Like leiomyomas, they can grow almost anywhere in the body. They are most often found in the retroperitoneum (area in back of the abdominal cavity), the internal organs, and blood vessels. These tumors are less often found in the deep soft tissues of the legs or arms. They tend to occur in adults, particularly the elderly. Leiomyosarcomas of the uterus are discussed in detail in our document, Uterine Sarcoma.

Rhabdomyosarcomas are malignant tumors of skeletal muscle. These tumors commonly grow in the arms or legs, but they can also begin in the head and neck area and in reproductive and urinary organs like the vagina or bladder. Children are affected much more often than adults. For more information, see our document, Rhabdomyosarcoma.


Peripheral nerve tissue tumors

The brain and spinal cord are parts of the central nervous system. The nerves that run throughout the body are part of the peripheral nervous system. Tumors can start in these peripheral nerves.

Benign nerve tumors

Neurofibromas, schwannomas (neurilemmomas), and neuromas are all benign tumors of nerves. These tumors can occur almost anywhere in the body. Neurofibromas are very common in people with an inherited condition called neurofibromatosis (also called von Recklinghausen disease). Sometimes neurofibromas of very large nerves (like those in the upper arms or neck) can become malignant.


Malignant nerve tumors

Neurofibrosarcomas, malignant schwannomas, and neurogenic sarcomas are malignant tumors of the cells that surround a nerve. These are also called malignant peripheral nerve sheath tumors.

Gastrointestinal stromal tumor (GIST) is a type of sarcoma that develops in the digestive tract. It starts in the cells that control the muscles lining the stomach and intestine. These muscles propel food through the digestive tract. GISTs are not discussed further in this document, but are covered in detail in our document, Gastrointestinal Stromal Tumor (GIST).


Joint tissue tumors

Our joints are surrounded by a capsule made of a tough tissue called synovium. This tissue produces a fluid that lubricates the joint surfaces so that they move smoothly. Tumors of joints can start in the synovium.

Benign joint tumors

Nodular tenosynovitis is a benign tumor of joint tissue. It is most common in the hands and is more common in women than in men.

Malignant joint tumors

Synovial sarcoma is a malignant tumor of the tissue around joints (the synovium). The most common locations are the knee and ankle. Other sites are the shoulder and hip. This tumor is more common in children and young adults, but it can occur in older people.


Blood and lymph vessels tumors

Benign vessel tumors

Hemangiomas are benign tumors of blood vessels. They are rather common and can affect the skin or internal organs. They are sometimes present at birth, and some disappear without treatment.

Lymphangiomas are benign lymph vessel tumors that are usually present at birth. Lymph is a fluid that circulates in every tissue of the body, ending up in the venous system. It carries waste products from tissues and immune system cells.

Glomus tumors are benign tumors that are found around blood vessels (perivascular). They usually are found under the skin of the fingers.


Intermediate vessel tumors

Hemangiopericytoma is another tumor of perivascular tissue. This tumor can be either benign or malignant. It most often starts in the legs, pelvis, and retroperitoneum (the back of the abdominal cavity). It is most common in adults. This type of tumor usually doesn’t spread to distant sites, but it does tend to come back in or near the same place that it started, even if it was removed completely at surgery.

Hemangioendothelioma is a blood vessel tumor that is considered a low-grade cancer (meaning it grows slowly and is slow to spread). It does grow into nearby tissues and sometimes can spread to distant parts of the body (metastasize). It may start in soft tissues or in internal organs, such as the liver or lungs.


Malignant vessel tumors

Angiosarcoma is a malignant tumor that can develop either from blood vessels (hemangiosarcomas) or from lymph vessels (lymphangiosarcomas). These tumors are linked to radiation exposure — they sometimes start in a part of the body that has been treated with radiation. Angiosarcomas are sometimes seen in the breast after radiation therapy for breast cancer, and in limbs that are chronically swollen because lymph circulation is blocked (lymphedema).

Kaposi sarcoma is a cancer formed by cells similar to those lining blood or lymph vessels. In the past, Kaposi sarcoma was an uncommon cancer mostly seen in older people with no apparent immune system problems. But it is now seen more often in people with suppressed immune systems (from HIV infection and in organ transplant patients). It is not discussed further in this document, but is covered in detail in our document, Kaposi Sarcoma.


Fibrous tissue tumors

Fibrous tissue forms tendons and ligaments and covers bones as well as other organs in the body.

Benign fibrous tumors

These include:

  • Fibromas
  • Elastofibromas
  • Superficial fibromatosis
  • Fibrous histiocytomas


Intermediate fibrous tumors

Fibromatosis is the name given to fibrous tissue tumor with features in between fibrosarcoma and benign tumors such as fibromas and superficial fibromatosis. They tend to grow slowly but, often, steadily. These tumors are also called desmoid tumors, as well as the more scientific name musculoaponeurotic fibromatosis. They do not spread to distant sites, but they do cause problems by growing into nearby tissues. They can sometimes be fatal. Some doctors consider them a type of low-grade fibrosarcoma; but others believe they are a unique type of fibrous tissue tumors. Certain hormones, particularly estrogen, make some desmoid tumors grow. Anti-estrogen drugs are sometimes useful in treating desmoids that cannot be completely removed by surgery.

Dermatofibrosarcoma protuberans is a slow-growing cancer of the fibrous tissue beneath the skin, usually in the trunk or limbs. It grows into nearby tissues but rarely spreads to distant sites.


Malignant fibrous tumors

Fibrosarcoma is cancer of fibrous tissue. It usually affects the legs, arms, or trunk. It is most common in people between the ages of 20 and 60, but can occur at any age, even in infancy.


Uncertain tissue type tumors

Doctors look at tumor tissue under the microscope and do other tests and can usually find similarities between most sarcomas and certain types of normal soft tissues. But some sarcomas have not been linked to a specific type of normal soft tissue.


Benign uncertain tissue type tumors

Myxoma is a benign tumor that usually is located in muscles but does not start from muscle cells. The cells of a myxoma produce mucus-like material, a feature that distinguishes this tumor. It almost always occurs in adults.

Granular cell tumors are usually benign tumors in adults that occur often in the tongue but can be found almost anywhere in the body.

PEComa is a family of tumors made up of abnormal cells called perivascular epithelial cells. Although most of these tumors are benign, some rare PEComas are malignant (cancer). The most common PEComas are angiomyolipoma and lymphangioleiomyomatosis (LAM). Angiomyolipoma is a benign tumor that most often affects the kidney. LAM is a disease of women in which the tumor cells grow into the lung tissue and interfere with lung function.

Malignant uncertain tissue type tumors

Malignant mesenchymoma is a rare type of sarcoma that contains some areas showing features of fibrosarcoma and other areas with features of at least 2 other types of sarcoma.

Alveolar soft-part sarcoma is a rare cancer that mostly affects young adults. These tumors most commonly occur in legs.

Epithelioid sarcoma most often develops in tissues under the skin of the hands, forearms, feet, or lower legs. Adolescents and young adults are often affected.


Clear cell sarcoma is a rare cancer that often develops in tendons of the arms or legs. Under the microscope, it shares some features with malignant melanoma, a type of cancer that develops from pigment-producing skin cells. How cancers with these features start in parts of the body other than the skin is not known.


Desmoplastic small round cell tumor is a rare sarcoma of adolescents and young adults, found most often in the abdomen. Its name means that it is formed by small, round cancer cells surrounded by scar-like tissue.


Pleomorphic undifferentiated sarcoma, also known as malignant fibrous histiocytoma (MFH), is most often found in the arms or legs. Less often, it can start inside the back of the abdomen. This sarcoma is most common in older adults. Although it mostly tends to grow locally, it can spread to distant sites.


Spindle cell tumor and spindle cell sarcoma are named based on the long, narrow appearance of the cells under the microscope). A spindle cell tumor is a tumor with cells that look like these. Spindle cell tumor is not a specific diagnosis or a specific type of cancer. The tumor may be a sarcoma, or it can be sarcomatoid — meaning another type of tumor (like a carcinoma) that looks like a sarcoma under the microscope.


Other types of sarcoma

There are other types of tumors called soft tissue sarcomas, but these are all quite rare.

Tumor-like conditions of soft tissue

Some conditions of soft tissues are caused by inflammation or injury and can form a mass that looks like a soft tissue tumor. Unlike a true tumor, they do not come from a single abnormal cell, they have limited capacity to grow or spread to nearby tissues, and never spread through the bloodstream or lymph system. Nodular fasciitis and myositis ossificans are 2 examples which involve tissues under the skin and muscle tissues, respectively.


What are the risk factors for soft tissue sarcomas?

A risk factor is anything that changes your chance of getting a disease like cancer. Different cancers have different risk factors. For example, unprotected exposure to strong sunlight is a risk factor for skin cancer. Smoking is a risk factor for cancers of the lung, and many other cancers. But risk factors don’t tell us everything. Having a risk factor, or even several, doesn’t mean that you will get the cancer. Also, many people get cancer without having a risk factor.

Scientists have found a few risk factors that make a person more likely to develop soft tissue sarcomas.

Radiation exposure

Patients might develop sarcomas from radiation given to treat other cancers, like breast cancer or lymphoma. The sarcoma often starts in the area of the body that had been treated with radiation. The average time between radiation exposure and diagnosis of a sarcoma is about 10 years. Radiation exposure accounts for less than 5% of sarcomas.

Radiation therapy techniques have improved steadily over several decades. Treatments now target the cancers more precisely, and more is known about selecting radiation doses. These advances are expected to reduce the number of cancers caused by radiation therapy. But because these cancers take so long to develop, the results of these changes may not be seen for a long time. Still, radiation therapy is used only when its benefits (improved survival rate and relief of symptoms) outweigh the risk of cancer and other complications. For more information, see our document Second Cancers Caused by Cancer Treatment.

Genetic syndromes

Certain inherited conditions increase a person’s risk of developing soft tissue sarcomas.


Neurofibromatosis is a disease that usually runs in families and is characterized by many neurofibromas (benign tumors that form in nerves under the skin and in other parts of the body). It is also known as von Recklinghausen disease. It is caused by a defect (mutation) in a gene called NF1. About 5% of people with neurofibromatosis will develop a malignant peripheral nerve sheath tumor in a neurofibroma.

Gardner syndrome

Gardner syndrome is a disease caused by defects in the gene APC. People with this syndrome get many polyps in the colon (and intestines) and have a high risk of getting colon cancer. It also causes musculoaponeurotic fibromatosis (also called desmoid tumors). Some experts consider desmoid tumors a slow-growing (low-grade) type of fibrosarcoma.

Li-Fraumeni syndrome

Li-Fraumeni syndrome is caused by inherited defects in the gene TP53. People affected by this syndrome have a high risk of cancer, such as breast cancer, brain tumors, and sarcomas. People with this syndrome are sensitive to the cancer-causing effects of radiation − if their cancer is treated with radiation, they have a very high chance of developing a new cancer in the part of the body that received the radiation.


Retinoblastoma is an eye cancer in children that can be caused by defects in the gene RB1. Children with one of these gene defects also have an increased risk of developing bone or soft tissue sarcomas, especially if treated for cancer with radiation.

Werner syndrome

Werner syndrome is caused by defects in the gene RECQL2. Children with this syndrome have problems like those seen in the elderly. These include cataracts, skin changes, and clogged heart arteries (arteriosclerosis) which can lead to heart attacks. They also have an increased risk of cancer, including soft tissue sarcomas.

Gorlin syndrome

Gorlin syndrome, also called nevoid basal cell carcinoma syndrome, is caused by defects in the PTCH1 gene. People with this syndrome have a high risk of developing many basal cell skin cancers. They also have an increased risk of getting fibrosarcoma and rhabdomyosarcoma.

Tuberous sclerosis

Tuberous sclerosis can be caused by a defect in the TSC1 gene. It can also be caused by a defect in another gene: TSC2. People with this syndrome often have seizures and learning problems. They get benign tumors in many different organs. They also get kidney problems, often along with a kidney tumor called angiomyolipoma. People with tuberous sclerosis have an increased risk of getting rhabdomyosarcoma.

Damaged lymph system

Lymph is a clear fluid containing immune system cells that is carried throughout the body by a series of lymph vessels. These vessels connect lymph nodes (small bean-shaped collections of immune system cells). When lymph nodes have been removed by surgery or damaged by radiation therapy, lymph fluid can build up. This is called lymphedema. In some parts of the world, severe lymphedema (a condition called elephantiasis) is sometimes caused by infection with a parasite that blocks lymph vessels.

Lymphangiosarcoma (a malignant tumor that develops in lymph vessels) is a very rare complication of chronic lymphedema.


Exposure to vinyl chloride (a chemical used in making plastics) is a risk factor for developing sarcomas of the liver, but it has not been proven to cause soft tissue sarcomas. Arsenic has also been linked to a type of liver sarcoma but not soft tissue sarcoma. Exposure to dioxin and to herbicides that contain phenoxyacetic acid at high doses (such as might occur to people who work on farms) may also be risk factors, but this is not known for certain. There is no evidence that herbicides (weed killers) or insecticides, at levels encountered by the general public, cause sarcomas.


An injury is not a risk factor for developing sarcomas. But this issue has caused some confusion in the past. One reason is that injury may produce a swelling that resembles a tumor but is not a true tumor. Also, when you are injured, the pain may draw your attention to the injured area. The area may be examined closely, and x-rays or other imaging studies may be obtained. This can make it more likely that any sarcoma that is present will be discovered, even though it may have been present for some time.


Can soft tissue sarcomas be found early?

People who have a strong family history of sarcomas or who have had other cancers when they were young, might wish to discuss the benefits and disadvantages of genetic testing with their doctor. The genetic testing results should always be explained by a genetic counselor or a specially trained doctor who can interpret the results and advise high-risk patients about early cancer detection.

Families with a history of certain inherited conditions (see the section, “What are the risk factors for soft tissue sarcomas?”) caused by mutated tumor suppressor genes have an increased risk of developing soft tissue sarcomas. The mutated genes can be detected by genetic testing, so family members should discuss this option with their doctors. They should let their doctor know about any lumps or growths right away.

No screening tests and exams are recommended for people who have no family history of sarcoma or other sarcoma risk factors. For these people, the best approach to early detection is to notify their health care professional of any unexplained lumps or growths or other symptoms that may be caused by a soft tissue sarcoma.


How are soft tissue sarcomas treated?

This information represents the views of the doctors and nurses serving on the American Cancer Society’s Cancer Information Database Editorial Board. These views are based on their interpretation of studies published in medical journals, as well as their own professional experience.

The treatment information in this document is not official policy of the Society and is not intended as medical advice to replace the expertise and judgment of your cancer care team. It is intended to help you and your family make informed decisions, together with your doctor.

Your doctor may have reasons for suggesting a treatment plan different from these general treatment options. Don’t hesitate to ask him or her questions about your treatment options.

General treatment information

After a sarcoma is found and staged, the cancer care team will recommend one or several treatment options. This is an important decision, so take time and think about all of the choices. In choosing a treatment plan, factors to consider include the type, location, and stage of the cancer, as well as your overall physical health.

The main types of treatment for soft tissue sarcoma are:

  • Surgery
  • Radiation
  • Chemotherapy
  • Targeted therapy

It is often a good idea to seek a second opinion. A second opinion can provide more information and help you feel more confident about the treatment plan that is chosen. Some insurance companies require a second opinion before they will agree to pay for treatments.


What should you ask your doctor about soft tissue sarcomas?

As you cope with cancer and cancer treatment, you need to have honest, open discussions with your doctor. You should feel comfortable asking any question no matter how small it might seem. Nurses, social workers, and other members of the treatment team may also be able to answer many of your questions.

  • What kind of sarcoma do I have?
  • How much experience do you have in diagnosing and treating sarcoma?
  • Has my cancer spread?
  • What is the stage of my cancer and what does that mean?
  • What are my treatment choices?
  • What treatment do you recommend and why?
  • What risks or side effects are there to the treatments you suggest?
  • What are the chances my cancer will come back with these treatment plans?
  • What should I do to be ready for treatment?
  • What’s my outlook?

In addition to these sample questions, be sure to write down some of your own. For instance, you might want more information about recovery times so that you can plan your work schedule. Or you may want to ask about second opinions or about clinical trials for which you may qualify.


What happens after treatment for soft tissue sarcomas?

For some people with soft tissue sarcoma, treatment may remove or destroy the cancer. Completing treatment can be both stressful and exciting. You may be relieved to finish treatment, but find it hard not to worry about cancer coming back. (When cancer comes back after treatment, it is called recurrence.) This is a very common concern in people who have had cancer.

It may take a while before your fears lessen. But it may help to know that many cancer survivors have learned to live with this uncertainty and are leading full lives. Our document, Living With Uncertainty: The Fear of Cancer Recurrence, gives more detailed information on this.

For other people, the cancer may never go away completely. These people may get regular treatments with chemotherapy, radiation therapy, or other therapies to try to help keep the cancer in check. Learning to live with cancer that does not go away can be difficult and very stressful. It has its own type of uncertainty. Our document, When Cancer Doesn’t Go Away, talks more about this.

Follow-up care

When treatment ends, your doctors will still want to watch you closely. It is very important to go to all of your follow-up appointments. During these visits, your doctors will ask questions about any problems you have and might do exams and lab tests or x-rays and scans to look for signs of cancer or treatment side effects. Almost any cancer treatment can have side effects. Some may last for a few weeks to months, but others can last the rest of your life. This is the time for you to talk to your cancer care team about any changes or problems you notice and any questions or concerns you have.

It is important to keep health insurance. Tests and doctor visits cost a lot, and even though no one wants to think about their cancer coming back, this could happen.

Should your cancer come back, our document, When Your Cancer Comes Back: Cancer Recurrence can give you information to help you manage and cope with this phase of your treatment.

Seeing a new doctor

At some point after your cancer diagnosis and treatment, you may find yourself seeing a new doctor who does not know anything about your medical history. It is important that you be able to give your new doctor the details of your diagnosis and treatment. Make sure you have the following information handy:

  • A copy of your pathology report(s) from any biopsies or surgeries
  • If you had surgery, a copy of your operative report(s)
  • If you were hospitalized, a copy of the discharge summary that doctors prepare when a patient is sent home
  • If you had radiation, a copy of your radiation treatment summary
  • If you had chemotherapy (including hormone therapy or targeted therapy), a list of your drugs, drug doses, and when you took them
  • Copy of recent imaging studies (such as x-rays, CT scans, and MRI scans) on a DVD plus the radiology reports.

The doctor may want copies of this information for his records, but always keep copies for yourself.


What`s new in soft tissue sarcoma research and treatment?

Research is ongoing in the area of soft tissue sarcomas. Scientists are learning more about causes and ways to prevent sarcomas, and doctors are working to improve treatments.

Basic research

Scientists have made progress in understanding how certain changes in the DNA of soft tissue cells cause sarcomas to develop. This information is already being applied to new tests to diagnose and classify sarcomas. This is important because accurate classification helps doctors select the most appropriate treatment. It is hoped that this information will soon lead to new strategies for treating these cancers, based on specific differences between normal and malignant soft tissue cells.


Classification of most cancers, including sarcomas, is based mostly on the way they look under a microscope. Recent research has shown that several different kinds of soft tissue sarcomas can look very similar under the microscope. By using new lab methods, researchers discovered that most cancers that used to be called malignant fibrous histiocytoma (MFH) are actually high-grade forms of liposarcoma, rhabdomyosarcoma, leiomyosarcoma, other sarcomas, and even carcinomas or lymphomas. About 10% to15% of cancers called MFH before, still cannot be given a precise classification, and these are now called pleomorphic undifferentiated sarcomas or undifferentiated pleomorphic sarcomas (although the current classification system of the World health Organization permits use of MFH as an alternate name).


Active research in chemotherapy for soft tissue sarcomas includes studies of new drugs and new ways to give drugs now available.

A new drug called trabectedin (Yondelis®) has been shown to help some patients with soft tissue sarcomas. It is approved for use in Europe, but it is still being tested in the United States. In this country, it is currently only available as part of a clinical trial.

Targeted therapy

Even more active than research into chemotherapy is research into so-called targeted drugs. These are drugs that specifically block molecules in the cancer cells that cause the cancers to grow.

Other targeted drugs may also be helpful against sarcomas. For example, one type of sarcoma, gastrointestinal stromal tumor (discussed in a separate document) can be treated with a drug called imatinib (Gleevec®). This drug is also helpful in treating desmoid tumors. Another targeted drug, sunitinib (Sutent®), seems to slow the growth of many sarcomas. Sirolimus (Rapamune®) has shown some promise in treating patients with PEComa, especially pulmonary lymphangioleiomyomatosis.

Anti-angiogenesis drugs

Drugs that block new blood vessel formation may help kill sarcomas by preventing their nourishment by the blood vessels. One such drug, bevacizumab (Avastin®) has shown a small benefit in sarcoma patients, when given with doxorubicin. Other anti-angiogenesis drugs are currently being studied as treatment for sarcomas.

Radiation therapy

Studies of radiation therapy methods, for example, the roles of external beam radiation and brachytherapy (internal radiation) are also in progress. Use of intraoperative (during surgery) radiation therapy for abdominal and retroperitoneal sarcomas is being tested.