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

• Gastric Synovial Sarcoma
• Primary Gastric Synovial Sarcoma
• Synovial Cell Sarcoma of Stomach

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

• In general, 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, 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
• Synovial Sarcoma of Stomach is an extremely uncommon and malignant mesenchymal (non-epithelial) tumor. The tumor is predominantly seen in younger populations (children and teenagers)
• The cause of formation of this gastric tumor may be due to genetic and chromosomal abnormalities. No definitive risk factors are observed for Synovial Sarcoma of Stomach
• Small tumors may be painless and asymptomatic, while advanced cases present abdominal pain, unintended weight loss, and fatigue. In case of a delayed diagnosis, metastasis of the sarcoma to other distant regions may occur
• The treatment of choice for Gastric Synovial Sarcoma is a surgical excision with clear margins followed by radiation therapy/chemotherapy. In case of spread of cancer to other regions, a combination of treatments may be considered by the healthcare provider
• The prognosis depends upon a set of several factors including the stage of the tumor, extent of tumor spread, overall health of the patient, and many other factors. In general, the prognosis of Synovial Sarcoma of Stomach is guarded

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

• Synovial Sarcoma of Stomach is a very rare tumor and only a few cases have been documented
• It is generally observed in children, teens, and young and middle-aged adults
• Both males and females are affected

• All races and ethnic groups are at risk for the tumor

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

The risk factors for Synovial Sarcoma of Stomach are not well-established. 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 one’s 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 Stomach? (Etiology)

The exact cause and mechanism of formation of Synovial Sarcoma of Stomach 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.
• Many cancer types are caused by genetic mutations. These can occur, due to inherited mutations, or mutations that occur due to environmental factors 
• 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 Stomach?

Synovial Sarcoma of Stomach may present the following signs and symptoms:

• Initially, small-sized tumors may be asymptomatic
• Most tumors occur as a mucosal or submucosal mass
• The small-sized tumors are about 2-3 cm in dimension, while some grow to be large-sized tumor masses (over 10 cm in size)
• Small tumors appear as a plaque or depression on the gastric surfaces
• Commonly observed symptoms for advanced cancer are abdominal pain and discomfort
• The tumor may be located anywhere in the stomach
• Large tumors may cause a pressure effect by compressing adjoining structures and organs
• Large tumors may ulcerate and bleed and become painful; this may result in blood in stool
• Involvement of lymph nodes may be noted in advanced tumor cases

How is Synovial Sarcoma of Stomach Diagnosed?

A diagnosis of Synovial Sarcoma of Stomach may involve the following:

• Complete physical exam with evaluation of medical history
• Ultrasound scan of the stomach/abdomen: It is a non-invasive procedure that uses high frequency sound waves to produce real-time images
• Abdominal CT scan: It is a noninvasive procedure that provides more details of soft tissues, blood vessels, and internal organs
• Stool sample analysis
• Upper GI endoscopy: An endoscopic procedure is performed using an instrument called an endoscope, which consists of a thin tube and a camera. Using this technique, the radiologist can have a thorough examination of the insides of the gastrointestinal tract
• Chromoendoscopy can help detect small-sized tumors; small tumors can also be detected using narrow band imaging technique
• Endoscopic ultrasonography: During this procedure, fine needle aspiration biopsy (FNAB) can be performed on the affected area. This is good technique for tumor detection, including tumor invasion parameters, and whether nearby lymph nodes are affected
• Esophagogastroduodenoscopy (EGD): It is a procedure to check the linings of the esophagus, stomach, and duodenum. Through this procedure, biopsies may be performed at the same time. It is generally preferred for evaluating individuals with suspected stomach cancer
• Vascular angiographic studies of the tumor
• Exploratory laparoscopy (diagnostic laparoscopy) may be required, if gastrointestinal symptoms are present. In this procedure, the abdomen is examined using a minimally-invasive technique, and a tissue biopsy and tissue for culture obtained
• Whole body PET scans to determine how far the cancer has spread to other organ systems

Although the above modalities can be used to make an initial diagnosis, a tissue biopsy of the tumor is necessary to make a definitive diagnosis to begin treatment. The tissue for diagnosis can be procured in multiple different ways which include:

• Fine needle aspiration (FNA) biopsy of the tumor: A FNA biopsy may not be helpful, because one may not be able to visualize the different morphological areas of the tumor and the tumor may be misdiagnosed. Hence, a FNA biopsy as a diagnostic tool has certain limitations, and an open surgical biopsy is preferred
• Core biopsy of the tumor 
• Open biopsy of the tumor

Tissue biopsy:

• A tissue 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 special studies, which may include immunohistochemical stains, molecular testing, and very rarely, electron microscopic studies to assist in the 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 of Stomach?

The complications of Synovial Sarcoma of Stomach may include the following:

• Ulceration of the tumor can lead to secondary infections of bacteria and fungus
• Compression of the underlying nerve, which can affect nerve function
• Perforation or rupture of the stomach
• The tumor can metastasize to the local or distant lymph nodes; metastasis to other body organs
• Recurrence of the tumor following treatment
• Side effects of chemotherapy (such as toxicity) and radiation
• Damage to the muscles, vital nerves, and blood vessels, during surgery
• Post-surgical infection at the wound site is a potential complication

How is Synovial Sarcoma of Stomach Treated?

There are no well-established treatment protocols available to treat Synovial Sarcoma of Stomach, since it is a very rare tumor. Nevertheless, a combination of surgery, chemotherapy, and radiation therapy are advocated. The treatment may also depend upon the stage, overall health, age, and subtype of the tumor.

• When the tumor is confined to the surface, then endoscopic mucosal/submucosal resection (or surgical removal via endoscopy) is undertaken
• Gastrectomy or surgery to remove part (or all) of the stomach, termed subtotal (partial) gastrectomy or total gastrectomy respectively
• Embolization is used to provide temporary relief from the symptoms and reduce blood loss during a surgical procedure
• If the tumor has metastasized, then a combination of chemotherapy, radiation therapy, and invasive procedures may be used to treat the tumor
• Clinical trial therapies (especially for stage IV disease) including therapeutic drugs, radiation, stem cell transplantation, and monoclonal antibodies, either singly or in combination of various therapies
• Palliative care is provided for advanced cancer stages
• Follow-up care with regular screening and check-ups are very important and encouraged

How can Synovial Sarcoma of Stomach be Prevented?

• Current medical research has not established a method of preventing the formation of Synovial Sarcoma of Stomach
• 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 metastasizing potential and chances of recurrence, often several years of active follow-up and vigilance is recommended

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

• The prognosis of Synovial Sarcoma of Stomach is generally guarded. But, the prognosis depends upon a set of several factors, which 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
  • Overall health of the individual
  • Age of the individual: Older individuals generally have poorer prognosis than younger individuals
  • The size of the tumor: Individuals with small-sized tumors fare better than those with large-sized tumors
  • Individuals with bulky disease may have a poorer prognosis
  • Involvement of vital organs may complicate the condition
  • The surgical resectability 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: Tumors that respond to treatment have better prognosis compared to tumors that do not respond to treatment; good response to treatment (surgery and/or chemotherapy/radiation therapy)
  • 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
• It has been reported that small tumors when removed completely show good prognosis, if the tumors are not poorly-differentiated and do not show high cell activity (mitotic activity)
• The combination chemotherapy drugs used, may have some severe side effects (such as cardio-toxicity). This chiefly impacts the elderly adults, or those who are already affected by other medical conditions. Tolerance to the chemotherapy sessions is a positive influencing factor

Additional and Relevant Useful Information for Synovial Sarcoma of Stomach:

The following DoveMed website links are useful resources for additional information:

http://www.dovemed.com/diseases-conditions/cancer/