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Synovial Sarcoma of Lung

Last updated Jan. 4, 2019

Approved by: Krish Tangella MD, MBA, FCAP


CT scan of lung showing sarcoma of the lung.

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

  • Primary Synovial Sarcoma of Lung
  • Pulmonary Synovial Sarcoma
  • SS of Lung

What is Synovial Sarcoma of Lung? (Definition/Background Information)

  • A synovial sarcoma (SS) is a malignant tumor of the connective tissue, involving the tendon sheath and synovial cells of the joints. However, a synovial sarcoma is not confined to the joint locations alone; but may occur in soft tissues, all over the body. The main sites are the lower limb joints, followed by the head and neck region
  • Synovial Sarcoma of Lung is a rare malignancy of the lung. However, the lung is the most frequently involved ‘organ’ by synovial sarcoma. The tumor is mostly observed as a nodule in the lung periphery
  • The tumors can be locally infiltrative and cause obstructive signs and symptoms including chest pain and breathing difficulties. Synovial Sarcoma of Lung is mostly observed in middle-aged and older adults
  • Currently, there are no identified risk factors or cause for Synovial Sarcoma of Lung, though certain chromosomal translocations have been identified
  • The treatment of Pulmonary Synovial Sarcoma is undertaken through surgery. However, since it may be difficult to remove the entire tumor, chemotherapy and/or radiation therapy may be necessary
  • The prognosis of Synovial Sarcoma of Lung is generally poor due to respiratory complications, local invasion, and metastasis of the cancer to various body sites

Who gets Synovial Sarcoma of Lung? (Age and Sex Distribution)

  • Synovial Sarcoma of Lung is a rare soft tissue malignancy of the lung
  • The tumor occurs mostly in older adults; the average age of diagnosis is 42 years
  • Both males and females are affected and no gender preference is seen
  • There is no racial or ethnic group predilection observed

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

Currently, no specific risk factors are noted for the development of Synovial Sarcoma of Lung. However, the following factors may be linked to synovial sarcoma, in general:

  • Some reports indicate an association with exposure to asbestos
  • Radiation therapy performed for Hodgkin lymphoma

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 of Lung? (Etiology)

The exact cause and mechanism of formation of Synovial Sarcoma of Lung is unknown. But, it has been proposed that certain chromosomal translocation leading to gene abnormalities, may be the initiator of synovial sarcoma development.

  • In general, it is known that cancers form when normal, healthy cells begin transforming into abnormal cells - these cancer cells grow and divide uncontrollably (and lose their ability to die), resulting in the formation of a mass or a tumor
  • The transformation of normally healthy cells into cancerous cells may be the result of genetic mutations. Mutations allow the cancer cells to grow and multiply uncontrollably to form new cancer cells
  • These tumors can invade nearby tissues and adjoining body organs, and even metastasize and spread to other regions of the body

What are the Signs and Symptoms of Synovial Sarcoma of Lung?

The signs and symptoms of Synovial Sarcoma of Lung may include:

  • Synovial sarcomas are firm, well-circumscribed, and solitary in appearance
  • Bulky, large-sized tumors may be seen; these tumors are locally infiltrative
  • A majority of the tumors are observed in the periphery (outer lung) invading into the lung tissue
  • Some grow to large sizes and the mediastinum or chest wall may be occasionally involved
  • The presence of a well-circumscribed nodule with an average size of 7.5 cm (size range is between 6 mm to 17 cm)
  • Imaging studies may reveal pleural invasion with effusion (fluid in the chest); involvement of the bones or calcification is not typically observed
  • Chest pain, breathing difficulties and shortness of breath, blood in cough, dizziness, and fainting may be present

Small tumors may not present any significant signs and symptoms.

How is Synovial Sarcoma of Lung Diagnosed?

The following tools may be used towards establishing a diagnosis of Synovial Sarcoma of Lung:

  • Physical examination and complete medical history screening: During the physical exam, the healthcare provider may listen to the lung  with a stethoscope, to detect the presence of any abnormal lung sounds
  • Imaging studies that may include a chest X-ray, MRI or CT scan of the lungs
  • Arterial blood gases
  • Lung function test
  • Sputum cytology: This procedure involves the collection of mucus (sputum), coughed-up by the patient, which is then examined in a laboratory by a pathologist
  • Whole-body PET scan, bone scan of affected region to check for tumor metastasis. This helps with the staging of the tumor

A tissue biopsy refers to a medical procedure that involves the removal of cells or tissues, which are then examined by a pathologist. This can help establish a definitive diagnosis. The different biopsy procedures may include: 

  • Bronchoscopy: During bronchoscopy, a special medical instrument called a bronchoscope is inserted through the nose and into the lungs to collect small tissue samples. These samples are then examined by a pathologist, after the tissues are processed, in an anatomic pathology laboratory
  • Thoracoscopy: During thoracoscopy, a surgical scalpel is used to make very tiny incisions into the chest wall. A medical instrument called a thoracoscope is then inserted into the chest, in order to examine and remove tissue from the chest wall, which are then examined further
  • Thoracotomy: Thoracotomy is a surgical invasive procedure with special medical instruments to open-up the chest. This allows a physician to remove tissue from the chest wall or the surrounding lymph nodes of the lungs. A pathologist will then examine these samples under a microscope after processing the tissue in a laboratory
  • Fine needle aspiration biopsy (FNAB): During fine needle aspiration biopsy, a device called a cannula is used to extract tissue or fluid from the lungs, or surrounding lymph nodes. These are then examined in an anatomic pathology laboratory, in order to determine any signs of abnormality. Nevertheless, FNAB is not a preferred method for the biopsy of lung tumors
  • Autofluorescence bronchoscopy: It is a bronchoscopic procedure in which a bronchoscope is inserted through the nose and into the lungs and measure light from abnormal precancerous tissue. Samples are collected for further examination by a pathologist

Tissue biopsy of the tumor:

  • A biopsy of the tumor is performed and sent to a laboratory for a pathological examination. A pathologist examines the biopsy under a microscope. After putting together clinical findings, special studies on tissues (if needed) and with microscope findings, the pathologist arrives at a definitive diagnosis. Examination of the biopsy under a microscope by a pathologist is considered to be gold standard in arriving at a conclusive diagnosis
  • Biopsy specimens are studied initially using Hematoxylin and Eosin staining. The pathologist then decides on additional studies depending on the clinical situation
  • Sometimes, the pathologist may perform additional studies, which may include immunohistochemical stains, electron microscopy, and molecular studies to assist in the diagnosis

A differential diagnosis with respect to other lung tumor types may be necessary prior to establishing a definite diagnosis, by excluding the following tumors:

  • Ewing sarcoma
  • Malignant mesothelioma
  • Malignant peripheral nerve sheath tumor
  • Pleuropulmonary blastoma
  • Small cell carcinoma
  • Solitary fibrous tumor
  • Spindle cell carcinoma
  • Other smooth muscle sarcomas

Note: Synovial Sarcoma of Lung may be monophasic or biphasic. The monophasic subtype is much more common than the biphasic subtype.

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 of Lung?

Complications due to Synovial Sarcoma of Lung could include:

  • Metastasis of the tumor to other body sites: Any part of the body may be affected including the local and distant lymph nodes, brain, gastrointestinal tract, liver, spleen, bone, and skin
  • Recurrence (local) of the tumor after surgery, when the entire tumor is not removed
  • Blood loss during invasive treatment methods may be heavy
  • Damage of vital nerves, blood vessels, and surrounding structures during surgery
  • Side effects from chemotherapy (toxicity), radiation therapy

How is Synovial Sarcoma of Lung Treated?

The treatment measures for Synovial Sarcoma of Lung may include a combination of the following:

  • Surgery: Complete excision where possible is attempted; though, it may be difficult for this lung tumor to be removed completely
  • Radiation therapy and/or chemotherapy may be necessary to aid in the treatment
  • Embolization (clotting the vessels in the tumor) may be used to provide temporary relief from the symptoms and reduce blood loss during a surgical procedure
  • Lung transplantation may be undertaken in some cases; when no distant metastasis has occurred and the primary tumor, which cannot be surgically removed, is confined to the lung
  • Follow-up care with regular screening and check-ups are important

How can Synovial Sarcoma of Lung be Prevented?

  • Current medical research has not established a method of preventing the formation of Synovial Sarcoma of Lung
  • Due to its metastasizing potential and recurrence rate, regular medical screening at periodic intervals with blood tests, scans, and physical examinations, are mandatory for those who have already been treated for this tumor

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

  • The prognosis of Synovial Sarcoma of Lung is generally poor; most cases with local invasion or metastasis are fatal despite surgery to remove them
  • The overall 5 year survival rate is around 30%. Recurrence of the tumor can be high; between 25-75% of the tumors recur within 2 years
  • Unfavorable prognostic indicators include certain histological features (poorly-differentiated type, higher grade), high cell division rate, and large tumor sizes (over 5 cm in size)
  • The prognosis of lung cancer, in general, depends upon a set of several factors that include:
    • Stage of tumor: With lower-stage tumors, when the tumor is confined to site of origin, the prognosis is usually excellent with appropriate therapy. In higher-stage tumors, such as tumors with metastasis, the prognosis is poor
    • The size of the lung tumor: Individuals with small-sized tumors fare better than those with large-sized tumors
    • Overall health of the individual: Individuals with overall excellent health have better prognosis compared with those with poor health
    • Age of the individual: Older individuals generally have poorer prognosis than younger individuals
    • Individuals with bulky disease of the lung cancer have a poorer prognosis
    • Involvement of the lymph node, which can adversely affect the prognosis
    • Involvement of vital organs may complicate the condition
    • The surgical respectability of the tumor (meaning, if the tumor can be removed completely)
    • Whether the tumor is occurring for the first time, or is a recurrent tumor. Recurring tumors have worse prognosis compared to tumors that do not recur
    • Response to treatment of lung cancer: Tumors that respond to treatment have better prognosis compared to tumors that do not respond to treatment
    • Progression of the condition makes the outcome worse
  • An early diagnosis and prompt treatment of the tumor generally yields better outcomes than a late diagnosis and delayed treatment

Additional and Relevant Useful Information for Synovial Sarcoma of Lung:

  • Lung cancer incidence is around 35 cases per 100,000 populations: The incidence of lung cancer in non-smokers is 1-2 cases per 20,000 populations per year; its incidence in smokers is 20-30 times higher than that of non-smokers
  • Smoking is highly-associated with squamous cell carcinomas and small cell carcinomas; nevertheless, for all lung cancer forms, smoking is the single most important risk factor

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: Feb. 1, 2017
Last updated: Jan. 4, 2019