Chromosomal Translocations in the Diagnosis of Pediatric Soft Tissue Sarcoma

Abstract

Purpose : Pediatric soft tissue sarcomas have many similarity among different tumors. These tumors present small round cell types, and cause frequent diagnostic problems in pediatric pathology. An important advance in the investigation of these small round cell tumors has been the identification of consistent chromosomal translocations associated with several types of tumor. Method : Thirty six patients with soft tissue sarcoma were available for review. Seventeen cell lines were also included in this study. The RNA from the specimens were analyzed by reverse transcriptase-polymerase chain reaction (RT-PCR). Results : PAX 3-FKHR fusion was present in six of eight alveolar rhabdomyosarcoma and PAX 7-FKHR fusion was detected in two of eight alveolar rhabdomyosarcoma. None of the specimens expressed more than one chimeric transcript. EWS-FLI 1 or EWS-ERG fusions were detected in all ten Ewing's sarcoma. No specimens showed EWS-WT 1 fusion. These results corresponded well to the histopathologic diagnosis. There were no differences in the histologic appearances of tumors with the more frequent PAX 3-FKHR or EWS-FLI 1 fusions compared with those containing the variant PAX 7-FKHR or EWS-ERG fusions. Conclusion : RT-PCR assay for chimeric transcript is an useful tool for a rapid and objective diagnosis of pediatric solid tumors. Through these tools, we can approach genetically to the differential diagnosis of undifferentiated small round tumors.