RETROSPECTIVE ANALYSIS OF PLOIDY IN PRIMARY OSSEOUS AND EXTRAOSSEOUS EWING FAMILY TUMORS IN CHILDREN

Aims: To restrospectively study the DNA content in a series of childho od Ewing Family Tumors (EFT), and to investigate its prognostic value. Methods: The study was performed on a series of 27 EFTs (osseous Ewin g's sarcoma, 18 cases; extraossous Ewing's sarcoma, 2; peripheral neur oepithelioma, 4; Askin Rosai tumors, 3), Ploidy was investigated using both flow cytometry (FCM) and image cytometry (ICM) on tumor cell sus pensions from formalin-fixed paraffin-embedded specimens or fresh froz en tissue obtained from the primary tumor at diagnosis. Results: Ploid y was evaluable by FCM in all cases, and by ICM in 23/27. When fresh f rozen tissue and paraffin-embedded samples from the same tumor were av ailable for analysis, they yielded equal results. The rate of agreemen t between FCM and ICM was 82%. The majority of cases were diploid, and in the present series aneuploidy seemed to be associated with a poor outcome. Conclusions: These results suggest that aneuploidy could be a n indicator of a bad prognosis in EFT; however, the small number of ca ses precludes any conclusion of statistical value. Larger restrospecti ve studies on ploidy using archival material could be performed and th eir reliability is supported by the concordance of results from fresh and formalin-fixed tissue.