Immunohistochemical detection of MYC protein correlates with MYC gene status in aggressive B cell lymphomas

Aims: MYC gene translocation entails a bad prognosis and a poor response to rituximab-cyclophosphamide, doxorubicin, vincristine and prednisone (R-CHOP) in diffuse large B cell lymphomas (DLBCL), and more intensive chemotherapy regimens could be more effective in those cases. Its evaluation requires cytogenetic or fluorescence in-situ hybridization (FISH) studies, which are expensive and not widely available. The aim of this work was to find an immunohistochemical marker able to be used as a screening tool to identify MYC translocations. Methods and results: Aggressive B cell lymphomas in which MYC status was assessed during their diagnostic work-up between 2007 and 2010 were collected, their immunophenotype was re-evaluated, and were stratified according to the Hans algorithm. Two tissue microarrays were built in order to evaluate MYC protein expression with a commercially available antibody. The study was performed on 56 specimens: nine Burkitt lymphomas (eight translocated), 45 DLBCLs (nine translocated) and two lymphomas with intermediate features (both translocated). Only MYC protein expression detected by immunohistochemistry correlated with MYC translocation. No relationship was seen between MYC gene copies and protein expression. Conclusions: MYC protein expression detected by immunohistochemistry using a commercially available antibody correlates with MYC gene translocation, and could be used as a screening tool to select those cases in which confirmatory genetic testing is mandatory.