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.