{"type":"root","children":[{"type":"paragraph","children":[{"type":"text","value":"Expression of SS18-SSX fusion protein is the hallmark of Synovial Sarcoma, a type of soft tissue sarcoma that accounts for 5-10% of all soft tissue sarcoma. SS18-SSX is a fusion oncoprotein created during chromosome translocation in which the SS18 gene on chromosome 18 is fused to the SSX1, SSX2, or SSX4 gene on the X chromosome. In normal cells, SS18 subunit and BAF47 subunit bind to the BAF (mSWI/SNF) complex which produces polycomb-mediated repression of SOX-2 and cessation of proliferation. SS18-SSX fusion renders the BAF chromatin remodeling complex aberrant through the addition of SSX to the SS18 subunit and the loss of the BAF47 subunit from the BAF (mSWI/SNF) complex. The altered complexes reverse the polycomb-mediated repression and result in the activation of SOX-2 and uncontrolled proliferation. Diagnosis of Synovial Sarcoma can be challenging due to histologic overlap with a range of other tumors, therefore, IHC is routinely used in differential diagnosis."}]}]}