OBJECTIVE
To investigate the expression of the chimeric genes resulting from the specific chromosomal translocations in soft tissue sarcomas (STS) and its diagnostic significance for STS.
METHODS
The variety of fusion transcripts were detected in 103 cases of STS, including 30 cases of synovial sarcoma (SS), 15 cases of rhabdomyosarcoma (RMS), 25 cases of Ewing's sarcoma/peripheral primitive neuroectodermal tumors (ES/pPNET), 12 cases of dermatofibrosarcoma protuberans (DFSP), 14 cases of aveolar soft part sarcoma (ASPS), 3 cases of leiomyosarcoma (LMS), 2 cases of malignant fibrous histocytoma (MFH), and 2 cases of fibrosarcoma (FS); and 20 cases of control tumors by reverse transcription-polymerase chain reaction (RT-PCR) using formalin fixed, paraffin embedded specimens.
RESULTS
Of the 34 cases of SS 28 (93.3%) expressed SSX-SYT chimeric transcripts (14 were positive for SYT-SSX1, 9 for SYT-SSX2). Four of the six cases of alveolar RMS had a PAX3/PAX7-FKHR fusion transcript. None of the 9 cases of embryonic and polymorphic RMS expressed PAX3/PAX7-FKHR. Of the 25 cases of ES/pPNET, 19 were positive for EWS-FLI1 fusion transcript and 1 for EWS-ERG fusion transcript. COL1A1-PDGFB fusion transcript was expressed in 8 of the 12 cases (66.7%) of DFSP. Of the fourteen cases of ASPS, ten expressed ASPL-TFE3 fusion transcript. None of the 3 cases of LMS, 2 cases of MFH, 2 cases of FS, and 20 control cases contained any of the fusion transcript.
CONCLUSION
Chimeric gene transcript resulting from specific chromosomal translocations is a reliable index for the molecular diagnosis of STS and RT-PCR assay for detection of specific fusion gene provides a useful tool for confirmation of the diagnosis of STS in diagnostically difficult cases and in retrospective studies.