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Comparison of genetic, antigenic and clinical features of extra-osseous Ewing Sarcoma (EO-EWS) and osseous Ewing sarcoma

Comparison of genetic, antigenic and clinical features of extra-osseous Ewing Sarcoma (EO-EWS) and osseous Ewing sarcoma (O-EWS) . Amanda Rivera-Begeman; Carrye Cost; Stephen Lessnick; Richard Smith; Charles Timmons; Patrick Leavey Annual CTOS Meeting; Seattle, Washington, November 2007.

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Comparison of genetic, antigenic and clinical features of extra-osseous Ewing Sarcoma (EO-EWS) and osseous Ewing sarcoma

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  1. Comparison of genetic, antigenic and clinical features of extra-osseous Ewing Sarcoma (EO-EWS) and osseous Ewing sarcoma (O-EWS) Amanda Rivera-Begeman; Carrye Cost; Stephen Lessnick; Richard Smith; Charles Timmons; Patrick Leavey Annual CTOS Meeting; Seattle, Washington, November 2007

  2. Background • Ewing's sarcoma family of tumors (EFT) • Osseous EWS (O-EWS), Extraosseous ES (EO-EWS), Peripheral primitive neuroectodermal tumor (pPNET) and Askin's tumor of chest wall (Carvajal,R. et al; Hematol Oncol Clin North Am 2005) • Cell surface protein MIC-2 (CD99) expressed on both O-EWS and EO-EWS (Ambros, IM; Cancer; 1991) • FLI-1 nuclear immunostain + ve in 70% of EWS and PNET cases (Folpe et al; Am J Surg Pathol; 2000)

  3. Background • EWS/FLI-1 is seen in patients with EFT (O’Sullivan,MJ et al; Hum Pathol; 2001) • Prior reports of treatment for EO-EWS demonstrated no advantage to the addition of Doxorubicin (Raney RB et al.; J Clin Oncol; 1997) • EO-EWS should be treated with strategies used for O-EWS vs. malignant mesenchymal tumors (Castex,M.P.; J Clin Oncol; 2007)

  4. Objective • To describe genetic, antigenic, and clinical features of patients with EO-EWS, primarily those of intra-abdominal origin • To compare genetic and antigenic features of EO-EWS to those of randomly chosen patients with O-EWS

  5. Patients • Eligibility criteria • EFT treated at Children’s Medical Center Dallas (1995 – 2005; n=52) • Availability of archival diagnostic material and clinical data

  6. Patients

  7. Methods • All immunostains were independently reviewed by 2 pathologists (CT, ARB) • Interpretation was subjective +ve vs. –ve • No grading was attempted

  8. Fli-1 weak positive Fli-1 strong positive

  9. CD99 (O13) Weak positive CD99 (O13) strong positive

  10. Results – positive staining

  11. Results – positive staining

  12. Cytokeratin Cam 5.2 positive Carcinoembryonic antigen (CEA) positive

  13. Results – positive staining

  14. Results – positive staining

  15. Results – positive staining

  16. Methods • RT-PCR • RNA extracted from formalin fixed, paraffin embedded tumor (Roche high pure RNA paraffin kit) • PCR was performed for EWS/FLI-1 • EWS/FLI-1 fusion type identified by melt curve analysis • EWS-FLI-1 fusion type confirmed by agarose gel electrophoresis • Alternate partners were examined as necessary (ews/fev, etv1, etv4 and erg)

  17. Results – EWS-FLI-1 type • Not type 1 or 2 • EO-EWS: confirmed t(11:22)(q24;q12) but no translocation products amplified • O-EWS: PCR product melting curve between types 1 and 2 but failed sequencing

  18. Summary • Negative FLI-1 nuclear staining does not exclude EWS-FLI-1 translocation positive EFT • While CEA +ve staining can be seen in EO-EWS it does not differentiate this from O-EWS • More type 2 fusions noted in patients with EO-EWS

  19. Conclusion • Variability may occur in immunostaining and genotype analysis of patients with extra-osseous Ewing sarcoma vs. osseous Ewing sarcoma.

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