Detection of SYT-SSX fusion transcripts in both epithelial and spindle cell areas of biphasic synovial sarcoma using laser capture microdissection

To investigate the distribution of tumour cells expressing the SYT-SSX fusi on gene in biphasic synovial sarcoma, modified reverse transcription polyme rase chain reaction (RT-PCR) analysis was performed using microdissected sp ecimens from haematoxylin and eosin stained sections of archival paraffin w ax embedded tissues. This modified RT-PCR included a stage with degenerate oligonucleotide primed (DOP) PCR, which randomly amplified cDNA after rever se transcription. SYT-SSX fusion transcripts were detected in both epitheli al and spindle cell areas of all three biphasic synovial sarcomas examined. Subsequent sequence analysis confirmed that the detected messages were der ived from the SYT-SSX1 fusion gene in two cases and from SYT-SSX2, in one. These results indicate that SYT-SSX fusion transcripts are found in both ep ithelial and spindle cell areas of biphasic synovial sarcoma, and RT-DOP-PC R-PCR analysis is a useful method for detection of extremely small amounts of mRNA in microdissected samples from archival formalin fixed, paraffin wa x embedded tumour tissues.