Background Ewing＇s sarcoma/peripheral primitive neuroectodermal tumor （ES/pPNET） is often difficuh to distinguish from other small round cell tumors. The EWS-Ets gene fusions that result from chromosomal translocat...Background Ewing＇s sarcoma/peripheral primitive neuroectodermal tumor （ES/pPNET） is often difficuh to distinguish from other small round cell tumors. The EWS-Ets gene fusions that result from chromosomal translocations in this tumor provide potential molecular diagnostic markers. To apply these molecular markers to commonly available archival materials, we evaluated the feasibility of detecting EWS-Ets including EWS-Flil and EWS-ERG fusion transcripts in paraffin-embedded tissues and its diagnostic value for detecting ES/pPNET. Methods Thirteen paraffin-embedded samples of ES/pPNETs were retrieved from archives. Thirteen cases of other tumors with small round cell features （including rhabdomyosarcoma, neuroblastoma, lymphoma, small ceil carcinoma, and desmoplastic small round cell tumor ） were used as negative controls. β-actin and β2- microglobulin were used as internal controls. A nested reverse transcriptase-polymerase chain reaction （RT- PCR）-based assay was performed to detect the EWS-Flil and EWS-ERG fusion transcripts. Results β-aetin and β2-mieroglobulin were detected in 10/13 and 13/13 ES/pPNETs, respectively. EWS- Flil fusion transcripts were detected in 11 of 13 （85%） ES/pPNETs. Three chimeric transcripts, all EWS-Flil, were detected in ES/pPNET samples. Among 11 EWS-Flil-positive cases, 7 eases had a type Ⅰ fusion transcript involving fusion of EWS exon 7 with Flil exon 6, 2 eases had a type Ⅱ fusion transcript involving EWS exon 7 with Flil exon 5, and 2 eases expressed fusion transcripts involving EWS exon 7 and Flil exon 8. Type Ⅰ EWS- Flil fusion predominated over other types. Fusion types could not be distinguished in the remaining 2 eases. Thirteen negative controls did not show detectable chimeric messages. There was a significant relationship between EWS-Flil fusion transcripts and CD99 expression. Conclusions Molecular detection of EWS-Flil fusion transcripts in formalin-fixed paraffin-embedded material by nested RT-PCR is feasible and is useful for the diagnosis and differential diagnosis of ES/pPNETs.展开更多
文摘Background Ewing＇s sarcoma/peripheral primitive neuroectodermal tumor （ES/pPNET） is often difficuh to distinguish from other small round cell tumors. The EWS-Ets gene fusions that result from chromosomal translocations in this tumor provide potential molecular diagnostic markers. To apply these molecular markers to commonly available archival materials, we evaluated the feasibility of detecting EWS-Ets including EWS-Flil and EWS-ERG fusion transcripts in paraffin-embedded tissues and its diagnostic value for detecting ES/pPNET. Methods Thirteen paraffin-embedded samples of ES/pPNETs were retrieved from archives. Thirteen cases of other tumors with small round cell features （including rhabdomyosarcoma, neuroblastoma, lymphoma, small ceil carcinoma, and desmoplastic small round cell tumor ） were used as negative controls. β-actin and β2- microglobulin were used as internal controls. A nested reverse transcriptase-polymerase chain reaction （RT- PCR）-based assay was performed to detect the EWS-Flil and EWS-ERG fusion transcripts. Results β-aetin and β2-mieroglobulin were detected in 10/13 and 13/13 ES/pPNETs, respectively. EWS- Flil fusion transcripts were detected in 11 of 13 （85%） ES/pPNETs. Three chimeric transcripts, all EWS-Flil, were detected in ES/pPNET samples. Among 11 EWS-Flil-positive cases, 7 eases had a type Ⅰ fusion transcript involving fusion of EWS exon 7 with Flil exon 6, 2 eases had a type Ⅱ fusion transcript involving EWS exon 7 with Flil exon 5, and 2 eases expressed fusion transcripts involving EWS exon 7 and Flil exon 8. Type Ⅰ EWS- Flil fusion predominated over other types. Fusion types could not be distinguished in the remaining 2 eases. Thirteen negative controls did not show detectable chimeric messages. There was a significant relationship between EWS-Flil fusion transcripts and CD99 expression. Conclusions Molecular detection of EWS-Flil fusion transcripts in formalin-fixed paraffin-embedded material by nested RT-PCR is feasible and is useful for the diagnosis and differential diagnosis of ES/pPNETs.
