What Is Synovial Sarcoma?

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Synovial sarcoma is a type of cancer that affects soft tissues in the body.

These tumors are often found near joints in the arms and legs, but they can also grow in organs found in the chest and abdomen.

This article will give an overview of the symptoms, causes, diagnosis, treatment, and prognosis for synovial sarcoma.

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What Is Synovial Sarcoma?

Synovial sarcoma is part of a larger group of cancers called soft tissue sarcomas. These cancers start in soft tissues such as fat, muscles, tendons, blood vessels, lymphatic vessels, and nerves. The tumors most commonly occur in the leg, around the knee joint.

Synovial sarcoma is a relatively rare condition, making up only 5% to 10% of all soft tissue sarcomas. In the United States, one or two out of every one million people are diagnosed with this condition.

Synovial sarcoma is a bit different than other types of cancers because it commonly occurs in teenagers and young adults. In fact, one-third of people diagnosed with this type of cancer are under the age of 30. Most other types of cancer appear in adulthood.

3 Subtypes of Synovial Sarcoma

There are three subtypes of synovial sarcoma that are made up of different types of cells: monophasic, biphasic, and poorly differentiated.

  • Monophasic synovial sarcoma is made up of mainly spindle cells, which are named for their shape.
  • Biphasic contain spindle cells as well as epithelial cells, which are cells that can be found in the lining of your body.
  • Poorly differentiated cells of synovial sarcoma are often small, round, abnormal-looking cells.


Symptoms of synovial sarcoma are often not noticeable early on. These tumors are typically slow growing, and symptoms can go unnoticed for years before a diagnosis is made. As the tumor grows, the first thing a person might notice is swelling or a lump in the area of the cancer.

If the tumor is pressing on a nerve, pain can be the first sign of this condition. Because synovial sarcoma often grows near joints, a person might also experience a loss of range of motion as the tumor prevents the bones from moving freely.


The exact cause of synovial sarcoma is unknown. However, there are certain risk factors, such as a history of radiation treatment for other cancers and damage to the lymphatic system, that can increase a person’s chance of getting this condition. Exposure to environmental toxins such as radon, lead, and mercury can also increase the risk of developing cancer.

Genetic conditions, which can be inherited from your parents or develop at birth, can also increase the risk of synovial sarcoma. These include:


Radiographs, or X-rays, are commonly done early on in the process of diagnosing synovial sarcoma. X-rays, which provide images of bones and joints, can show damage to these structures near the tumor.

Ultrasound, or imaging using sound waves, can provide information in the early stages of diagnosis of synovial sarcoma. This testing helps determine whether a mass is fluid-filled, like a cyst, or a solid mass, like a tumor.

Computed tomography scans, or CT scans, are useful for diagnosing synovial sarcoma and can help determine if cancer has spread. Magnetic resonance imaging (MRI) and positron emission tomography (PET) scan are also commonly used.

Doctors may further use a needle to take a biopsy, or small sample of tissue, from the tumor. The tissue is then examined under a microscope to determine what the tumor is made of.


Treatment of synovial sarcoma depends on several things, such as the person’s age, where the tumor is, how large it is, and whether or not the cancer has spread to other areas. Most commonly, the first step in treatment is surgically removing the tumor.

Chemotherapy might be required after surgery to kill any remaining cancer cells or treat cancer that has spread to other areas. High doses of radiation can also be used to kill cancer cells and shrink tumors. In some cases, doctors might use these therapies to shrink a tumor prior to surgery as well.


As with other cancers, the prognosis after a diagnosis of synovial sarcoma depends on many factors. These include:

  • Tumor size
  • Where the tumor is located
  • Patient age at diagnosis
  • Nerve or bone involvement
  • Whether or not the cancer has spread

In general, large-sized tumors have a worse prognosis. Tumors that occur in the arms and legs (as opposed to internal organs) tend to lead to higher survival rates. People who have synovial sarcoma in childhood also have better survival rates.

The Importance of Early Detection

Prognosis for synovial sarcoma improves with earlier detection and treatment of the tumor before it has spread to other areas of the body.

A Word From Verywell

While synovial sarcoma is a relatively rare condition, early detection of cancer is key for improved prognosis. Talk to your doctor if you notice a lump, develop pain, or have difficulty moving your joints. They may be able to rule out this condition.

If you have been diagnosed with synovial sarcoma, remember that new treatments are developing all the time. Follow your doctor’s treatment plan and consider joining a support group to improve your quality of life.

6 Sources
Verywell Health uses only high-quality sources, including peer-reviewed studies, to support the facts within our articles. Read our editorial process to learn more about how we fact-check and keep our content accurate, reliable, and trustworthy.
  1. National Cancer Institute. Synovial sarcoma.

  2. Gazendam AM, Popovic S, Munir S, Parasu N, Wilson D, Ghert M. Synovial sarcoma: a clinical reviewCurr Oncol. 2021;28(3):1909-1920. doi:10.3390/curroncol28030177

  3. El Beaino M, Araujo DM, Lazar AJ, Lin PP. Synovial sarcoma: advances in diagnosis and treatment identification of new biologic targets to improve multimodal therapyAnn Surg Oncol. 2017;24(8):2145-2154. doi:10.1245/s10434-017-5855-x

  4. National Institutes of Health. Synovial sarcoma.

  5. American Cancer Society. Risk factors for soft tissue sarcomas.

  6. American Cancer Society. Tests for soft tissue sarcomas.

By Aubrey Bailey, PT, DPT, CHT
Aubrey Bailey is a physical therapist and professor of anatomy and physiology with over a decade of experience providing in-person and online education for medical personnel and the general public, specializing in the areas of orthopedic injury, neurologic diseases, developmental disorders, and healthy living.