Discussion
Synovial sarcoma is a form of soft tissue sarcoma that occurs mostly in young and middle-aged adults and has more tendency to occurs in extrimities,however,it can occurs in children and old individuals and involve other parts of the body (12, 13).It is believed that 5-10 percent of soft tissue sarcomas are synovial sarcoma.The tumor is closely related to tendon sheath,tendon,joint capsule and bursal structures (14).It may also arise primarily in other parts of the body,such as heart,kidney and lungs (3).There are four subtypes of synovial sarcoma,as mentioned bellow: monophasic, monophasic epithelial, biphasic, and poorly differentiated(round cell tumors)(3, 15). Classical synovial sarcoma has a biphasic morphology and it’s pathological findings are sheets of spindle cells and sharply segregated epithelial cells forming gland-like areas. A second form of synovial sarcoma is monophasic containing only a sarcomatous component. Most of the synovial sarcomas are of these two forms mentioned above (4).Because of the tumor resemblance to synovial tissue under light microscope,it was named “Synovial Sarcoma” by Sabrazes in 1934 (16).However,the cellular origin of this tumor is possibly from neural crest-derived malignant peripheral nerve cells (3). Chromosomal translocation of t(X;18)(p11.2;q11.2) can be investigated in over 95% of synovial sarcomas (4). the treatment of choice for primary tumors is excisional surgery,while metastatic synovial sarcoma can’t be treated with excisional surgery but chemotherapy and radiotherapy may help them (17).In some patients,synovial sarcoma is diagnosed when it reach out other organs such as lungs,bone and lymphnodes(5, 8, 18).Intracranial synovial sarcoma is very rare and in most cases are reported as a metastasis from synovial sarcoma (19). Synovial sarcoma presenting as an intracranial has been reported very rarely,as mentioned bellow:
1-Kleinschmidt-DeMasters et Al reported the case of a 19-year-old woman with primary synovial sarcoma of the third ventricle (20),
2- Bettio et Al reported a 36-year-old man with a large intracranial tumor involving the cranial base, with invasion to the sellar region and sphenoidal sinus (21) .
3-Mohit Patel et Al reported a primary intracranial synovial sarcoma as a right parietal heterogeneous, hyperdense mass with a large medial hematoma in a 21-year- old man (19) .
4-Yang-Yang Wang et Al reported a 35- year-old man with left intracerebral lesions with hemorrhage and left middle cerebral artery arteriovenous malformation, respectively (22).
The clinical manifestations of primary intracranial Synovial Sarcoma are nonspecific,such as headache, nausea, vomiting, hemiplegia.Radiologic features of primary synovial sarcoma are also nonspecific and the final diagnosis is made by pathological and immunohistochemistry features (22).
Our patient was a 28-year-old man with headache and left hemiplegia.Neurological examination revealed left sided hemiplegia,without gait instability and ataxia.Brain computed tomography(CT) scan revealed an intra axial mass lesion with central necrotic component and surrounding vasogenic edema in right frontal white matter causing midline shift to the left side.The patient underwent magnetic resonance imaging (MRI) with gadolinium contrast for more evaluation,and the findings were as mentioned bellow:An Intra axial well-circumscribed heterogenous mass with central necrosis and irregular peripheral enhancement and significant surrounding vasogenic edema in right frontal white matter.restriction of peripheral solid component of mas was also seen.The patient was taken to the operation room and underwent total excision of the mass.Many hours later the left hemiplegia was gradually improved.The histopathological assessment of the mass revealed neoplastic tissue composed of biphasic pattern: large irregular sheets of monotonous cells some with central necrosis set in fibroblastic stroma.Tumoral cells are plump and have very high N/C ratio.Frequent mitotic figures are present.
IHC staining show positive reactivity for TLE1,FEI1 and INI1 negative reactivity for Synaptophysin,Olig 2,SMA,CK CD 99.GFAP staining is nonspecific.Above findings are consistent with Synovial Sarcoma.PET scan didn’t show any other metastatic disease.Abdominopelvic CT scan was also normal.