Complex t(X;18)(p11.2;q11.2) with a pericentric inversion of the X chromosome in an adolescent boy with synovial sarcoma

Synovial sarcoma is the most common nonrhabdomyosarcomatous soft-tissue sarcoma in children and young adults. It is characterized by the common t(X;18)(p11.2;q11.2) that results in the fusion of SIT on chromosome 18 to one of two closely related and adjacent genes on the X chromosome, SSX1 or SSX2. Here we describe a poorly differentiated, monophasic synovial sarcoma in a 17-year-old adolescent boy. Hyperdiploidy, a t(X;18)(q13;q11), and other structural abnormalities were detected by conventional cytogenetic analysis. Fluorescence in situ hybridization with the PAC probe RP3-519N18, which is specific for the Xp11 region, resulted in a signal on the der(Xq), a finding consistent with a pericentric inversion of the X chromosome that resulted in a t(X;18)(p11.2;q11.2)inv(X)(p11.2q13). Real-time polymerase chain reaction using primer sets specific for SYT-SSX1 and SYT-SSX2 confirmed the presence of an SYT-SSX1 fusion transcript. Our finding of this unique and complex translocation in synovial sarcoma demonstrates the utility of molecular methods in confirming the diagnosis of synovial sarcoma. (C) 2002 Elsevier Science Inc. All rights reserved.