Validation of PRKCB Immunohistochemistry as a Biomarker for the Diagnosis of Ewing Sarcoma.

Ewing sarcoma (ES) can be confirmed by identifying the fusion transcript. This study is to investigate whether immunostaining (IHC) of PRKCB-a protein directly regulated by is a surrogate maker for diagnosing ES in routine practice. Microarray gene expression analyses were conducted. RKCB IHC was applied to 69 ES confirmed by morphology and molecular methods, and 41 non-Ewing small round cell tumors. or t(11;22)(q24;q12) were identified by fluorescence in situ hybridization, reverse transcriptase polymerase chain reaction, or cytogenetic analysis, respectively. Gene array analyses showed significant overexpression of the in ES. PRKCB IHC was positive in 19 cases of ES with EWSR1-FLI1 fusion, 3 cases with cytogenetic 11:22 translocation and 59 cases with EWSR1 rearrangement while negative in only one EWSR1 rearranged case. PRKCB IHC is sensitive (98%) and specific (96%) in detecting rearranged ES. PRKCB is a reliable antibody for diagnosing ES in routine practice.