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Definition of soft tissue sarcoma

A cancer that begins in the muscle, fat, fibrous tissue, blood vessels, or other supporting tissue of the body. 

Adult soft tissue sarcoma is a disease in which malignant (cancer) cells form in the soft tissues of the body

The soft tissues of the body include the muscles, tendons (bands of fiber that connect muscles to bones), fat, blood vessels, lymph vessels, nerves, and tissues around joints. Adult soft tissue sarcomas can form almost anywhere in the body, but are most common in the head, neck, arms, legs, trunk, and abdomen.

There are many types of soft tissue sarcoma. The cells of each type of sarcoma look different under a microscope, based on the type of soft tissue in which the cancer began.

See the following summaries for more information on soft tissue sarcomas:

Malignant peripheral nerve sheath tumor (MPNST)

Malignant peripheral nerve sheath tumors (MPNSTs) are sarcomas that originate from peripheral nerves or from cells associated with the nerve sheath, such as Schwann cells, perineural cells, or fibroblasts. Because MPNSTs can arise from multiple cell types, the overall appearance can vary greatly from one case to the next. This can make diagnosis and classification somewhat difficult. In general, a sarcoma arising from a peripheral nerve or a neurofibroma is considered to be a MPNST. The term MPNST replaces a number of previously used names including malignant schwannoma, neurofibrosarcoma, and neurogenic sarcoma.

A sarcoma is defined as a MPNST when at least one of the following criteria is met:

  • It arises from a peripheral nerve.
  • It arises from a preexisting benign nerve sheath tumor (neurofibroma).
  • It demonstrates Schwann cell differentiation on histologic examination.

Risk Factors

MPNSTs make up approximately 5-10% of all soft tissue sarcomas. They can occur either spontaneously or in association with neurofibromatosis-1 (NF1).

The cause of MPNST is unknown but there is a higher incidence in patients with a history of radiation exposure. Also, up to 50% of MPNSTs occur in patients with NF1, demonstrating the tendency for this tumor to arise from a preexisting neurofibroma.

MPNSTs generally occur in adulthood, typically between the ages of 20 and 50 years of age. Approximately 10-20% of cases have been reported to occur in the first 2 decade of life (Ref. 10), with occasional cases involving infants as young as 11 months of age.

Clinical features of MPNST

MPNSTs usually present as an enlarging palpable mass. Pain is a variable complaint. Rapid enlargement occurs more often in the setting of NF1 and should raise concern for malignant degeneration of a neurofibroma. MPNSTs arising from peripheral nerves may result in a variety of clinical patterns, including radiating nerve pain, paresthesias, and motor weakness. Most MPNSTs occur in conjunction with large peripheral nerves such as the sciatic nerve, the brachial plexus and the sacral plexus.


Recurrence can be discussed in terms of local disease and distant or metastatic disease. The local recurrence rate for MPNSTs has historically been reported to range from 40-65% and the distant recurrence rate has similarly been reported to range from 40-68%. Five-year survival has been reported to range from 16-52%. Longer survival has been correlated with complete surgical excision, small tumor size (<5 cm), and the presence of a low grade component.

One recent study showed a survival rate overall of 84% in patients treated at a sarcoma center. This has been largely attributed to improved imaging leading to early diagnosis and aggressive treatment, employing adjuvant and neoadjuvant treatment such as chemotherapy and radiation. In this study, patients with metastatic disease at presentation fared worse (33% survival) as would be expected.

While patients with NF1 were previously thought to have a worse prognosis than did patients with sporadic MPNSTs, recent reports fail to support this. 

Having certain inherited disorders can increase the risk of adult soft tissue sarcoma

Anything that increases your risk of getting a disease is called a risk factor. Having a risk factor does not mean that you will get cancer; not having risk factors doesn't mean that you will not get cancer. Talk with your doctor if you think you may be at risk. Risk factors for soft tissue sarcoma include the following inherited disorders:

  • Retinoblastoma.
  • Neurofibromatosis type 1 (NF1; von Recklinghausen disease).
  • Tuberous sclerosis (Bourneville disease).
  • Familial adenomatous polyposis (FAP; Gardner syndrome).
  • Li-Fraumeni syndrome.
  • Werner syndrome (adult progeria).
  • Nevoid basal cell carcinoma syndrome (Gorlin syndrome).

Other risk factors for soft tissue sarcoma include the following:

  • Past treatment with radiation therapy for certain cancers.
  • Being exposed to certain chemicals, such as Thorotrast (thorium dioxide), vinyl chloride, or arsenic.
  • Having swelling (lymphedema) in the arms or legs for a long time.

Possible signs of adult soft tissue sarcoma include a lump or swelling in soft tissue of the body

A sarcoma may appear as a painless lump under the skin, often on an arm or a leg. Sarcomas that begin in the abdomen may not cause symptoms until they become very large. As the sarcoma grows larger and presses on nearby organs, nerves, muscles, or blood vessels, symptoms may include:

  • Pain.
  • Trouble breathing.
Other conditions may cause the same symptoms that soft tissue sarcoma does. Check with your doctor if you have any of these problems.

Smooth muscle tumours

Smooth muscle lines the inside of blood vessels and hollow internal organs such as the stomach, intestines, bladder, and uterus.

  • Leiomyosarcoma: This smooth muscle tumour has been linked with Epstein-Barr virus in children who also have HIV /AIDS. Leiomyosarcoma may also form as a second cancer in survivors of inherited retinoblastoma, even many years after their treatment for retinoblastoma. 
  • Hemangiopericytoma: A hemangiopericytoma is not a meningeal tumour but is treated like a grade II or III meningioma. A hemangiopericytoma usually forms in the dura mater. The prognosis is worse than a grade I meningioma because the tumour usually cannot be completely removed by surgery.

Perivascular tumours

  • Myopericytoma: A rare, slow-growing soft tissue tumor that begins in cells that wrap around blood vessels. Most myopericytomas are benign (not cancer). They can occur anywhere in the body, but usually occur in the legs, trunk (chest and abdomen), or head and neck. They can occur in children, but are most common in middle-aged adults.
  • Glomangiopericytoma: Glomangiopericytoma is a rare vascular neoplasm characterized by a pattern of prominent perivascular growth. Glomangiopericytoma is categorized as a borderline low malignancy tumor by WHO classification. Long-term follow-up with systemic examination is necessary due to high risk of recurrence.

Adult soft tissue sarcoma is diagnosed with a biopsy 

If your doctor thinks you may have a soft tissue sarcoma, a biopsy will be done. The type of biopsy will be based on the size of the tumor and where it is in the body.

There are three types of biopsy that may be used:

  • Incisional biopsy: The removal of part of a lump or a sample of tissue.
  • Core biopsy: The removal of tissue using a wide needle.
  • Excisional biopsy: The removal of an entire lump or area of tissue that doesn’t look normal.

Samples will be taken from the primary tumor, lymph nodes, and other suspicious areas. A pathologist views the tissue under a microscope to look for cancer cells and to find out the grade of the tumor. The grade of a tumor depends on how abnormal the cancer cells look under a microscope and how quickly the cells are dividing.

High-grade tumors usually grow and spread more quickly than low-grade tumors.

Because soft tissue sarcoma can be hard to diagnose, patients should ask to have tissue samples checked by a pathologist who has experience in diagnosing soft tissue sarcoma.

The following tests may be done on the tissue that was removed:

  • Immunohistochemistry study: A laboratory test in which a substance such as an antibody, dye, or radioisotope is added to a sample of cancer cells to test for certain antigens. This type of study is used to tell the difference between different types of cancer.
  • Light and electron microscopy: A laboratory test in which cells in a sample of tissue are viewed under regular and high-powered microscopes to look for certain changes in the cells.
  • Cytogenetic analysis: A laboratory test in which cells in a sample of tissue are viewed under a microscope to look for certain changes in the chromosomes.
  • FISH (fluorescence in situ hybridization): A laboratory test used to look at genes or chromosomes in cells and tissues. Pieces of DNA that contain a fluorescent dye are made in the laboratory and added to cells or tissues on a glass slide. When these pieces of DNA attach to certain genes or areas of chromosomes on the slide, they light up when viewed under a microscope with a special light.
  • Flow cytometry: A laboratory test that measures the number of cells in a sample, the percentage of live cells in a sample, and certain characteristics of cells, such as size, shape, and the presence of tumor markers on the cell surface. The cells are stained with a light-sensitive dye, placed in a fluid, and passed in a stream before a laser or other type of light. The measurements are based on how the light-sensitive dye reacts to the light.

Certain factors affect treatment options and prognosis (chance of recovery)

The treatment options and prognosis (chance of recovery) depend on the following:

  • The type of soft tissue sarcoma.
  • The size, grade, and stage of the tumor.
  • How fast the cancer cells are growing and dividing.
  • Where the tumor is in the body.
  • Whether all of the tumor is removed by surgery.
  • The patient's age and general health.
  • Whether the cancer has recurred (come back).

For more information on Soft Tissue Sarcoma click here

This link is to the National Cancer Institute (NCI) cancer website in the United States. There may be references to drugs and clinical trials that are not available here in Australia.

Information has also been sourced from hindawi.comsarcoma.org.uk and sarcomahelp.org