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Synovial Sarcoma (SS)

Last updated Jan. 4, 2019

Approved by: Krish Tangella MD, MBA, FCAP


High magnification Microscopic pathology image of the lung showing monophasic synovial sarcoma. H&E stain.

What are the other Names for this Condition? (Also known as/Synonyms)

  • Adult Synovial Sarcoma
  • Biphasic Synovial Sarcoma
  • Malignant Synovial Sarcoma

What is Synovial Sarcoma? (Definition/Background Information)

  • A Synovial Sarcoma (SS) is a type of malignant tumor of the connective tissue, involving the tendon sheath and synovial cells of the joints. Synovium refers to the lubricating layer found in the joints (knee, elbow); synovium is responsible for making the synovial fluid
  • However, a Synovial Sarcoma is not confined to the joint locations alone; but, it may occur in soft tissues, all over the body. The main sites are the lower limb joints, followed by the head and neck region
  • The tumor has metastatic capability - meaning it can spread to other body locations, such as the lymph nodes, heart, kidney, lungs, and bone marrow. Individuals, below the age of 35 years, are commonly affected by this tumor
  • SS is treated using a combination of chemotherapy, radiation therapy, and invasive procedures. The long-term prognosis for the condition is poor in most individuals

Who gets Synovial Sarcoma? (Age and Sex Distribution)

  • A frequently occurring soft tissue tumor, Synovial Sarcoma usually affects teenagers and adults (below 35 years of age). However, it has been noticed in infants and very old individuals too
  • There is a slight male predominance
  • No ethnic or racial preference has been observed

What are the Risk Factors for Synovial Sarcoma? (Predisposing Factors)

A few genetic defects, occurring due to chromosomal translocation, have been identified as a recurring feature in many Synovial Sarcoma case study reports. Otherwise, no clear risk factors have been established.

The following factors have been potentially linked to Synovial Sarcoma:

  • Hip replacement (metal) implants
  • Radiation therapy performed for Hodgkin disease

It is important to note that having a risk factor does not mean that one will get the condition. A risk factor increases ones chances of getting a condition compared to an individual without the risk factors. Some risk factors are more important than others.

Also, not having a risk factor does not mean that an individual will not get the condition. It is always important to discuss the effect of risk factors with your healthcare provider.

What are the Causes of Synovial Sarcoma? (Etiology)

  • The exact cause of Synovial Sarcoma and mechanism of its formation is unknown
  • It has been proposed that certain chromosomal translocation (specifically, the translocation of genetic material between chromosome X and chromosome 18) leading to gene abnormalities, may be the initiator of SS development

What are the Signs and Symptoms of Synovial Sarcoma?

The presentations are based on the location of the tumor. Synovial Sarcoma signs and symptoms include:

  • In the initial growing phase of these generally deep tumors, they are asymptomatic. An individual (an adult or a child) may not experience any symptoms, until the tumor has grown into a substantial size
  • The soft tissue tumors grow initially at a moderate rate and then, suddenly start progressing rapidly in size
  • Due to large size of tumor growth, the adjoining organs, nerves, and muscles, may be compressed or restricted. Often these signs, along with pain and tenderness, may be the first indications of the tumor
  • Lesions beneath the skin may appear as a painful mass; though, subcutaneous Synovial Sarcomas are rare
  • Soft tissue mass location: The knees (almost 80% of the time), followed by the arms, trunk, head and neck, abdomen region, are the affected areas. Most tumors are observed around the joints or bones

How is Synovial Sarcoma Diagnosed?

A diagnosis of Synovial Sarcoma is made using the following tools:

  • Physical exam with evaluation of medical history
  • X-ray of affected joint or region
  • MRI and CT scans of the affected region
  • Tissue biopsy of the mass: Histopathological studies conducted on a biopsy specimen - the specimen is examined under a microscope by a pathologist, to arrive at a definitive diagnosis
  • Genetic testing and analysis, for detecting any chromosomal aberration
  • Differential diagnosis, to eliminate other tumor types is considered, before arriving at a definitive diagnosis

Many clinical conditions may have similar signs and symptoms. Your healthcare provider may perform additional tests to rule out other clinical conditions to arrive at a definitive diagnosis.

What are the possible Complications of Synovial Sarcoma?

Complications of Synovial Sarcoma are dependent on the site and stage of the tumor. These include:

  • Intestine, bone, or kidney damage, lung metastasis
  • Breathing or swallowing difficulties (if tumor mass obstructs the food pipe or wind pipe)
  • The mobility of the joints can be restricted, leading to difficulty in walking and performing normal daily activities, thereby affecting the quality of one’s life
  • Damage of the knee, elbow, or other organs; damage of vital nerves and blood vessels, during surgery
  • Usually by the time Synovial Sarcomas are detected, chances are that they would have proliferated and metastasized aggressively, damaging organs and tissues beyond repair
  • SS is known to having a high recurrence rate (50%), after surgical excision and removal
  • Side effects from chemotherapy (such as toxicity), radiation therapy

How is Synovial Sarcoma Treated?

Treatment measures for Synovial Sarcoma include the following:

  • Any combination of chemotherapy, radiation therapy, and invasive procedures are used to treat Synovial Sarcoma
  • Wide surgical excision with removal of the entire lesion is the standard treatment mode. If the tumor is not fully removed, then it might recur
  • Embolization is used to provide temporary relief from the symptoms, and reduce blood loss during a surgical procedure
  • When the tumor is at an inaccessible location, or is unsafe for surgical intervention; non-invasive procedures are adopted
  • Post-operative care is important: A minimum activity level is to be ensured until the surgical wound heals
  • Follow-up care with regular screening and check-ups are important, to watch for recurrence and any metastatic behavior

How can Synovial Sarcoma be Prevented?

  • Current medical research has not established a way of preventing Synovial Sarcoma occurrence
  • Regular medical screening at periodic intervals with blood tests, radiological scans, and physical examinations, are mandatory for those who have been diagnosed with the tumor
  • Due to its high metastasizing potential and chances of recurrence, often several years of active follow-up vigilance is necessary

What is the Prognosis of Synovial Sarcoma? (Outcomes/Resolutions)

  • Synovial Sarcomas are highly malignant cancers that are not yet completely understood through medical research
  • The long-term prognosis depends on a combination of factors, such as:
    • Age of the individual
    • Tumor stage at detection
    • Size, type, and location of the tumor
    • Ki-67 value (a protein found in cells that is a good indicator of cell activity)
    • Its response to treatment and medical therapy
  • The long-term outcome is poor for most individuals (36-76% mortality over a 5-year period); given its high recurrence and metastasizing rate
  • The best treatment practice for SS involve a combination of radiotherapy with surgical intervention, which is sometimes followed by post-surgical chemotherapy
  • The prognosis of Synovial Sarcoma is fairly good, when:
    • The tumor size is small (and also shows a low cell proliferation activity)
    • If the diagnosis reveals an absence of necrosis (tissue death)
    • And the patients are quite young

Additional and Relevant Useful Information for Synovial Sarcoma:

Synovial Sarcomas are histopathologically (which is the study of tissue cells and the effect of diseases on them) classified as Monophasic Synovial Sarcoma and Biphasic Synovial Sarcoma. The subtypes are confirmed by a pathologist, after examining the tissue under a microscope.

What are some Useful Resources for Additional Information?

References and Information Sources used for the Article:

Helpful Peer-Reviewed Medical Articles:

Reviewed and Approved by a member of the DoveMed Editorial Board
First uploaded: May 26, 2014
Last updated: Jan. 4, 2019