Detection of SYT-SSX1/2 fusion transcripts by reverse transcriptase-polymerase chain reaction (RT-PCR) is a valuable diagnostic tool in synovial sarcoma

Cytogenetically, most synovial sarcomas are characterised by a specific chr omosomal translocation [(X;18)(p11.2;q11.2)], which results in the generati on of fusion transcripts comprising SYT (18q11) and either SSX1 or SSX2 (Xp 11) sequences. By using a sensitive reverse transcriptase-polymerase chain reaction (RT-PCR) protocol, specific SYT-SSX1/2 fusion transcripts were det ected in 10 histopathologically confirmed synovial sarcomas. Control tumour s with morphological spindle cell patterns mimicking monophasic synovial sa rcoma tested negative (18/19) in the RT-PCR protocol, with the exception of one spindle cell sarcoma originally classified as a fibrosarcoma. Furtherm ore, the established RT-PCR protocol was used to evaluate the feasibility o f SYT-SSX1/2 fusion transcript detection for minimal residual disease analy sis. Analyses of surgical margins revealed a fusion transcript in two of fo ur operations for synovial sarcoma analysed, one of which was diagnosed wit h tumour free margins by conventional histopathology. These data suggest th at the RT-PCR amplification of SYT-SSX1/2 fusion transcripts is a valuable tool in the differentiation of synovial sarcomas, especially in cases of eq uivocal morphology. Additionally, the RT-PCR approach may be used for the d etection of residual tumour cells in synovial sarcoma patients. (C) 1998 El sevier Science Ltd. All rights reserved.