A sarcoma is a type of cancer that develops from certain tissues, such as bone or muscle. There are 2 main types of sarcoma: osteosarcoma, which develops from bone, and soft tissue sarcomas. Soft tissue sarcomas can develop from soft tissues such as 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 appears in 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 concentrates on 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.

Tumors of fat tissue

Benign fat tissue tumors

Lipomas are benign tumors of fat tissue. They are the most common benign soft tissue tumor. Most are found 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.

Tumors of muscle tissue

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 -- that is, 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 -- that is, voluntary movement.

Benign muscle tumors

Leiomyomas are benign tumors of smooth muscle (or involuntary muscle). Since leiomyomas can start from the walls of blood vessels, they can develop almost anywhere in the body. These tumors also can start in the walls of the intestine. Although they can be found in both men and women, 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 Sarcomas.

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 such as the vagina or bladder. Children are affected much more often than adults. For more information, see our document, Rhabdomyosarcoma.

Tumors of peripheral nerve tissue

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 (neurilemomas), 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 (such as 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 tumors (GIST) are a type of sarcoma that develops in the digestive tract. They start in the cells that control the muscles lining the stomach and intestine. These muscles propel food through the digestive tract. GIST is not discussed further in this document, but is covered in detail in our document, Gastrointestinal Stromal Tumors.

Tumors of joint tissue

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.

Tumors of blood and lymph vessels

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 type of 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 develops in the legs, pelvis, and retroperitoneum (the back of the abdominal cavity). It is most common in adults. This type of tumor doesn’t often 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 develop in soft tissues or in internal organs, such as the liver or lungs.

Malignant vessel tumors

Angiosarcomas are malignant tumors that can develop either from blood vessels (hemangiosarcomas) or from lymph vessels (lymphangiosarcomas). These tumors are linked to radiation exposure - they sometimes develop 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.

Tumors of fibrous tissue

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 these to be 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 (DFSP) 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.

Tumors of uncertain tissue type

By looking at tumor tissue under the microscope and doing other tests, doctors can usually find similarities between most sarcomas and certain types of normal soft tissues. However, 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 develop 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.

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 the 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 develop 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 develop 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 (such as a carcinoma) that looks like a sarcoma under the microscope.

Other types of sarcoma

There are other types of tumors called soft tissue sarcomas; however, 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. Examples include nodular fasciitis and myositis ossificans, which involve tissues under the skin and muscle tissues, respectively.

Last Medical Review: 03/03/2009
Last Revised: 05/14/2009