a 46-year - old married saudi woman presented at a primary health care center with left upper abdominal pain , with no other associated symptoms .
five months later , she presented to the surgery clinic because of increased abdominal pain with no response to medication ; her physical examination showed fullness of the left upper abdomen .
her routine laboratory investigation as well as chest and abdominal x - rays were not remarkable .
ultrasound of the abdomen showed a solid mass at the left hypochondrium separated from the spleen and just below the left hemidiaphragm . computed tomography ( ct )
scan of the abdomen ( figure 1 ) showed encapsulated hypodense mass at the left upper abdomen which was interposed but clearly separated from left liver lobe , spleen , stomach and left hemidiaphragm .
magnetic resonance imaging ( mri ) of the abdomen ( figure 2 ) confirmed the location of the mass and attachment to the inner aspect of the anterior abdominal wall but separated from internal abdominal organs .
the mass was isosignal intensity to muscles in t1- weighted images and heterogeneous hyperintense signal in t2 weighted images . in post
( a ) axial non - enhanced ct scan of the abdomen showing a well defined hypodense mass at the left hypchondrium , interposed between left liver lobe , left hemidiaphragm and stomach .
( a ) axial t1w1 : an oval shape mass with signal intensity parallel to the muscle .
( c ) axial post contrast t1w1 showing avid contrast enhancement of the mass . at surgery ,
a firm , rounded mass apparently encapsulated at the left sub - diaphragmatic area was found attached to the extra - peritoneal fascia of the anterior abdominal wall .
histopathology showed a biphasic tumor composed of spindle cell and epithelial cell elements , with mild anaplasia & infrequent mitosis .
the final diagnosis was low grade synovial sarcoma involving the fascial aponeurosis of the anterior abdominal wall .
synovial sarcoma ( ss ) is an uncommon soft - tissue malignant tumor that is common in the extremities of middle - aged patients , close to large joints particularly the knee in the popliteal fossa.12 despite its name , the lesion does not commonly arise in an intraarticular location but usually near joints .
the tumor arises from pleuripotential mesenchyme , in close association with joint capsules , tendon sheaths , bursae and fascial structures .
it is generally accepted that synovial sarcoma is derived from primitive mesenchymal cells , not synovial cells.2 synovial sarcoma is the fourth most common type of soft tissue sarcoma following malignant fibrous histiocytoma , liposarcoma and rhabdomyosarcoma .
synovial sarcoma accounts for 5 - 10% of all soft tissue sarcomas.3 about 85 - 90% of ss occur in the extremities.4 reported examples arising in the anterior abdominal wall are rare .
synovial sarcoma in the abdominal wall tends to occur with a much greater frequency in females in contrast to such tumors in the extremities or the neck which tend to occur with a much greater frequency in males.5 radiological findings of ss are not pathognomonic .
however , findings of a soft - tissue mass , particularly if calcified ( 30% ) , near but not in a joint of a young patient , are very suggestive of the diagnosis . cross - sectional imaging features are essential for staging extent of the tumor and the planning of surgical resection.6 the most common ct appearance of ss is that of a heterogeneous soft - tissue mass with attenuation similar to or slightly lower than that of muscle
areas of lower attenuation representing necrosis or hemorrhage are also common with heterogeneous contrast enhancement.7 on mri , ss typically appears as a prominently heterogeneous multilobulated soft - tissue mass with signal intensity similar to or slightly higher than that of muscle on t1-weighted mr images .
prominent heterogeneity with predominant high signal intensity is also a feature of ss on t2-weighted mr images .
the presence of multilobulation and marked heterogeneity are highly suggestive of a diagnosis of ss .
ct and mri are useful in defining the extent of the disease and in follow up response to chemotherapy.7 the presence of extensive calcification suggests a more favorable prognosis.8 similar ct and mri appearances are seen in our case . despite its name
there are three main histologic subtypes of ss : biphasic , monophasic , and poorly differentiated types .
poorly differentiated ss is generally epithelioid in morphology and has high mitotic activity.78 in the present case , histopathology showed a biphasic pattern of ss , the coexistence of spindle cells in a wavy pattern , and the pseudoglandular formation .
both biphasic and monophasic synovial sarcomas are usually intermediate grade ( grade 2/3 ) ; however , both types can be high grade ( grade 3/3 ) .
poorly differentiated synovial sarcomas are high - grade tumors.7 the specific chromosomal aberration in synovial sarcoma has recently been reported .
the hallmarks for synovial sarcoma are the ( x ; 18 ) translocation and syt - ssx gene fusion products .
is the molecular diagnosis in synovial sarcoma , as well as immunohistochemical study , especially in cases in which histological diagnosis is difficult.79 surgical excision is the treatment of choice , and the recurrence rate range from 28% to 36% even with adequate surgical and adjunctive therapies.4 however , the multimodality treatment approach has improved the prognosis of synovial sarcomas .
tumor invasiveness , histologic grade and tumor size significantly correlate with the survival period , with a more preferable prognosis of synovial sarcomas encountered in childhood .
chemotherapy has been used to treat metastatic or residual disease.710 primary synovial sarcoma of the anterior abdominal wall is a rare extra - articular tumor site . in cases of anterior abdominal wall masses ,
 synovial sarcoma is a malignant mesenchymal neoplasm which commonly occurs in the extremities of adults , in close association with joint capsules , tendon sheaths , bursae and fascial structures . 
 only a few cases of synovial sarcoma occurring in the abdominal wall have been reported . a case of a primary synovial sarcoma arising from the anterior abdominal wall fascial aponeurosis is presented . 
CASE REPORT
DISCUSSION