SS18 and synovial sarcoma: The cytogenetically defined translocation t(X;18)(p11.2;q11.2) found in human synovial sarcoma results in the fusion of the SYT gene on chromosome 18 to SSX1, SSX2, or SSX4 on chromosome X at Xp11.2, leading to the formation of SYT-SSX fusion transcript [3–5].