6.P.01 MOLECULAR TYPING FROM ARCHIVAL PARAFFIN-EMBEDDED SYNOVIAL SARCOMAS

Abstract

Synovial sarcomas are mesenchimal tumours with unde-fined histogenesis which represent 5–10% of soft tissues tumours; they are divided into different subtypes according to morphology and epithelial differentiation. From a molecular point of view, synovial sarcoma is characterized by t(X;18)(p11;q11) translocation which joins SYT gene with a member of SSX gene family. We developed an efficient method to detect the two main fusion transcripts SYT-SSX1 and SYT-SSX2 based on RT-PCR or Real-Time PCR applied to archival paraffine-embedded samples.

This study includes 49 patients surgically treated for synovial sarcoma and analyzed with routine immuno-histochemical analysis. We used alternatively nested-PCR or Real-Time PCR, with SYBR green method, to detect SYT-SSX transcripts: these techniques allowed us to discriminate between the two transcripts.

In 42 subjects out of 49 we could find a specific fusion transcript and, in particular, 31 patients were carriers of SYT-SSX1 translocation. Interestingly we could find 6 patients who were carriers of both SYT-SSX1 and SYT-SSX2 transcripts. We selected nine samples for Real-Time PCR analysis and we could quantify the reciprocal ratio between the two fusion transcripts when they were both present in the same sample.

The use of molecular techniques such as RT-PCR represents a sensitive and reliable tool as a support to histopathologic diagnosis of synovial sarcoma. Moreover, Real-Time PCR enormously enhances sensibility and enables to determine single transcript quantity when both SYT-SSX1 and SYT-SSX2 are present in the same sample. This method can also be used to reclassify those cases whose diagnosis is still undefined after routine analysis.