RESUMEN
<p><b>OBJECTIVE</b>To evaluate the application of fluorescence in-situ hybridization (FISH) in detection of gene translocation in paraffin-embedded tissue samples of synovial sarcoma.</p><p><b>METHODS</b>Interphase FISH was carried out in paraffin-embedded tissue of 42 cases of synovial sarcoma and 9 cases of non-synovial sarcoma, using a LSI SYT (18q11.2) dual color break-apart probe. In all of the cases studied, the gene fusion product SYT-SSX was also analyzed by reverse transcription-polymerase chain reaction (RT-PCR).</p><p><b>RESULTS</b>Positive signals were detected in 37 cases (88.1%) of synovial sarcoma by FISH, as compared with 35 cases (83.8%) by RT-PCR and 39 cases (92.9%) by both techniques. Of the 39 positive cases, 33 cases (78.5%) revealed SYT gene translocation.</p><p><b>CONCLUSIONS</b>FISH may serve as an adjunctive diagnostic tool in problematic cases of synovial sarcoma and can be applied in paraffin-embedded tissue samples. As compared with RT-PCR, FISH is also sensitive and reliable. The methodology is less labor intensive and time consuming. FISH has great potential in molecular diagnosis of soft tissue tumors.</p>