DIAGNOSIS OF SYNOVIAL SARCOMA WITH THE REVERSE TRANSCRIPTASE-POLYMERASE CHAIN-REACTION - ANALYSES OF 84 SOFT-TISSUE AND BONE-TUMORS

The chimeric transcript SYT-SSX is generated as a result of reciprocal translocation t(X;18), which is the primary cytogenetic abnormality f ound in, and appears to be specific for, synovial sarcoma. We performe d a reverse transcriptase-polymerase chain reaction (RT-PCR) for SYT-S SX transcripts in a series of 84 tumors (61 soft tissue tumors and 23 bone tumors), including a variety of histologic types, to assess its u sefulness in molecular diagnosis. Ten synovial sarcomas, three tumors initially unclassified, and one malignant peripheral nerve sheath tumo r contained the chimeric transcripts. A review of the original slides and additional examination showed that a diagnosis of synovial sarcoma was appropriate for these cases. Additionally, in situ hybridization with an SSX1 probe indicated that the chimeric transcripts exist not o nly in the cells of special components but also in cells showing a var iety of histologic patterns. Therefore, RT-PCR can be considered a use ful molecular biological technique that can provide objective evidence for diagnosis of synovial sarcoma. Northern blot analysis with an SSX 1 probe also detected chimeric SYT-SSX transcripts in the synovial sar coma cases. The additional smaller bands, however, were also detected in six peripheral primitive neuroectodermal tumors (pPNETs) and one em bryonal rhabdomyosarcoma. In five of these pPNETs, other bands ranging in size from 2.0 to 2.2 kb were also found, and it seems possible tha t these bands might represent novel karyotypic aberrations and/or spli cing variants of SSX.