Synovial sarcoma (SS) is the most common type of non-RMS in children and adolescents and accounts for about 35% of non-RMS.
Synovial sarcoma has a characteristic translocation: t(X;18)(p11.2;q11.2)
Origins:
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This tumor does not arise in relation to synovium and usually occurs on the extremities.
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SS would appear to be derived from skeletal muscle
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Almost all SS carry a demonstrable, pathognomonic t(X;18) reciprocal translocation fusing SS18 to an SSX gene
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SYT-SSX2 is the protein fusion product of the chromosomal translocation t(X;18)(p11.2;q11.2).
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SS18-SSX fusion oncoprotein is necessary and sufficient to support tumorigenesis
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SYT-SSX2 is
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Expressed in skeletal muscle lineage cells in mouse model
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Demonstrated by fluorescence in situ hybridization
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Known to associate with chromatin remodeling complexes and is proposed to be involved in controlling gene expression
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Plays a direct role in beta-catenin regulation
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Pathology:
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Concurrent epithelial and spindle cell proliferation
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Several subtypes:
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Biphasic (epithelial and spindle cell components)
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Monophasic fibrous type
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Monophasic epithelial type (less common)
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Poorly differentiated small cell neoplasm
TLE1 is used as a Diagnostic Immunohistochemical Marker in Synovial Sarcoma
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TLE1 encodes a transcriptional corepressor that is over-expressed in synovial sarcomas
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Gene and tissue microarray studies have identified TLE1 as an excellent bio-marker for distinguishing the synovial sarcoma from other soft tissue malignancies
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More sensitive and specific for synovial sarcoma than any other currently available immunohistochemical stains
Therapy
Management principles are the same as for any other non-RMS, however studies have shown that chemotherapy can improve disease free survival in this disease.
References and Resources
Chemotherapy Is Associated With Improved Survival in Adult Patients With Primary Extremity Synovial Sarcoma
