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.