Year : 2010 | Volume
: 53 | Issue : 1 | Page : 115--116
Intra articular synovial sarcoma
Radha Sistla, Afroz Tameem, JVS Vidyasagar
Department of Pathology, Vijaya Diagnostics Pvt Ltd, Hyderabad; Department of Orthopaedics, Kamineni Hospitals, L.B Nagar, Hyderabad, India
Plot No: 20, Road No:1, Alakapuri, Hyderabad-500 035
Synovial sarcoma is a soft tissue neoplasm with a characteristic biphasic pattern. Incidence in soft tissues is 5-10%. Intra articularly synovial sarcoma is extremely rare. Fewer than 5% of all synovial sarcomas arise within the joint space. We report a case of intra articular synovial sarcoma in a young male who presented as internal derangement of the knee.
|How to cite this article:|
Sistla R, Tameem A, Vidyasagar J. Intra articular synovial sarcoma.Indian J Pathol Microbiol 2010;53:115-116
|How to cite this URL:|
Sistla R, Tameem A, Vidyasagar J. Intra articular synovial sarcoma. Indian J Pathol Microbiol [serial online] 2010 [cited 2021 Oct 26 ];53:115-116
Available from: https://www.ijpmonline.org/text.asp?2010/53/1/115/59198
Synovial sarcoma is a misnomer as there is no clear synovial differentiation and these lesions rarely arise in the intra articular location. Less than 5% of synovial sarcomas arise within the joint space.  Synovial sarcomas arise in areas where there is no synovium like head and neck region or in the vein.  Synovial sarcomas secondarily invade joint capsule when they arise in close proximity to the joint but primary synovial sarcoma arising from articular synovium is extremely rare. Intra articular synovial sarcoma has been a subject of an abstract publication of six cases and two case reports.  We report a case of synovial sarcoma arising from articular synovium.
A 35-year-old man presented to orthopedic outpatient department with pain, limp and swelling of the right knee. He was asymptomatic until six months ago when he sustained injury to the right knee due to a trivial fall and underwent native treatment in the form of massages and bandaging for a week after which he was able to walk. The pain was dull aching in nature, poorly localized in the knee. On examination, there was atrophy of the quadriceps and swelling of the joint .Effusion was minimal with filling of para patellar fossa and patellar tap was negative. There was loss of terminal extension of the knee with 10-15 degrees of fixed flexion deformity and available range of movements was up to 100 degree of flexion. Tests for meniscal tears and ligament laxity were negative. Radiographs of the knee were normal and blood investigations and Mantoux test were non-contributory.
Diagnostic arthroscopy was done under general anesthesia and tourniquet control. Five ml of blood stained synovial fluid was found. Suprapatellar pouch, medial and lateral gutters, both menisci were normal. Articular surfaces of patella, femoral and tibial condyles were normal. Intercondylar area revealed a polypoidal lesion [Figure 1] in the synovial tissue which was excised and sent for histopathology examination. Anterior and posterior cruciate ligaments were covered by hypertrophied synovial tissue.
Pathological Findings: The gross specimen consisted of multiple gray white and gray brown bits measuring about two cms.
Microscopic Details: Sections revealed tissue lined by synovial cells with a cellular lesion in the subsynovial area. Cells are spindle shaped arranged in interlacing bundles and fascicles. Nuclei are elongated with fine chromatin clumping, mitoses were sparse. Interspersed in these spindle cells are cleft like and gland like structures lined by cuboidal to low columnar epithelium. Nuclei revealed fine chromatin clumping [Figure 2]. Immunohistochemistry revealed strong cytoplasmic expression of pancytokeratin [Figure 3] and epithelial membrane antigen in the glandular structures. Spindle cell elements expressed strong cytoplasmic vimentin positivity. Based on these findings a diagnosis of synovial sarcoma arising from the synovium was made.
The term synovial sarcoma was first introduced in 1936. The morphology of synovial sarcoma mimics a joint in its early stage of development. Cleft like spaces and glands simulate a joint space surrounded by subsynovial mesenchymal cells; hence the name "synovial sarcoma". Synovial sarcoma is extremely rare. There are few publications on synovial sarcoma in literature. 
We report a case of synovial sarcoma occurring in the articular synovium. Most of the patients are in the fourth or fifth decades of life. Patients range from nine to 49 years of age. Common presenting symptoms are internal derangement of the knee or joint effusion. Except one case from the elbow joint, all the other reported cases of intra articular synovial sarcoma are from the knee joint.  The case under discussion is a 35 year-old male with features of internal derangement of the knee joint. Radiological features are usually normal, one case revealed multiple erosions of adjacent bone. Intraarticular synovial sarcomas are polypoidal lesions with attachment to the joint capsule or there may be diffuse involvement of the synovial surface. 
Microscopically, majority of the cases are classical biphasic tumors, although a few monophasic tumors have also been described.  Extra articular synovial sarcoma occurring close to the major joints can invade joint capsule secondarily. Synovial sarcomas are locally aggressive lesions with 11% of lesions showing bone involvement. Lesions occurring in close proximity to joints also do not demonstrate synovial lining histologically. Differential diagnosis for intra articular synovial sarcoma includes localized villonodular synovitis. Localized villonodular synovitis may resemble a biphasic synovial sarcoma but the cells have an appearance of histiocytes. Localized villonodular synovitis is usually treated with local excision.
A tumor-specific SYT-SSX fusion transcript is described. This is a valuable tool for diagnostically difficult cases and tumors in unusual locations.  Our patient was treated with hinged knee replacement which includes excision of the lower end of femur up to supracondylar fossa - excision of intra articular synovium with a safe margin and one cm of the proximal tibial end. The patient has been on regular follow-up since the last 11 months with no radiological evidence of metastasis.
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