[Application of the in situ hybridization with EWS dual-color break-apart fluorescence probe and anti-CD99 and anti-FLI-1 antibodies in the diagnosis of Ewing's sarcoma/primitive neuroectodermal tumor].

OBJECTIVE: To investigate the value of using EWS dual-color, break-apart rearrangement probe fluorescence in situ hybridization (FISH) technique, CD99 and FLI-1 antibodies immunohistochemistry in the diagnosis of Ewing's sarcoma/primitive neuroectodermal tumor (EWS/PNET).

METHODS: Thirty-five cases of EWS/PNET and 24 cases of non-EWS/PNET small round cell tumor were analyzed by FISH and immunohistochemically detected with FLI-1 and CD99 antibodies. Comparison between FISH and immunohistochemical results was carried out and their diagnostic value was evaluated.

RESULTS: The sensitivity, specificity, positive predictive value and negative predictive value of FISH in EWS/PNET were 93.8%(30/32), 81.8%(18/22), 88.2%(30/34) and 90%(18/20); those of CD99 were 100%(35/35), 58.3% (14/24), 77.8%(35/45) and 100%(14/14); those of FLI-1 were 71.4%(25/35), 62.5%(15/24), 73.5%(25/34), 60%(15/25), respectively. The sensitivity, specificity, positive predictive value and negative predictive value of combined use of CD99 and FLI-1 were 71.4%(25/35), 75%(18/24), 80.6%(25/31) and 64.3%(18/28), those of combined use of FLI-1 and FISH were 68.7%(22/32), 86.4%(19/22), 88%(22/25) and 65.5%(19/29), those of combined use of CD99 and FISH were 93.7%(30/32), 95.5%(21/22), 96.8%(30/31) and 91.3%(21/23), respectively.

CONCLUSION: EWS dual-color, break-apart rearrangement probe FISH is a highly sensitive and specific technique in the diagnosis of EWS/PNET. The combination of CD99 and FISH is the method of choice for the diagnosis of EWS/PNET. The combination of CD99 and FLI-1 can improve the specificity in EWS/PNET without the data of FISH.