SS18 and sarcoma: SS is characterized by the presence of the pathognomonic t(X;18) (p11.2;q11.2) translocation, involving a fusion of the SS18 (formerly SYT) gene on chromosome 18 to one of the synovial sarcoma X (SSX) genes on chromosome X (usually SSX1 or SSX2), which is seen in more than 90% of SS and results in the formation of SS18-SSX fusion oncogenes [6].