FISH is better than BIOMED-2 PCR to detect IgH/BCL2 translocation in follicular lymphoma at diagnosis using paraffin-embedded tissue sections

The most common genetic aberration in follicular lymphoma (FL) is the t(14;18)(q32;q21) translocation that juxtaposes the antiapoptotic BCL2 gene with the promoter of the immunoglobulin heavy chain (IgH) gene. Our aim was to test the usefulness of two different techniques, fluorescence in situ hybridization (FISH) and PCR to detect t(14;18) in FL at diagnosis in paraffin-embedded tissue sections. A total of 51 patients diagnosed of FL were analyzed. FISH was performed with dual color dual fusion commercial probes (VYSIS) and in PCR experiments, the BIOMED-2 primers covering MBR, mcr and 3′MBR regions were applied. FISH showed positivity for the IgH/BCL2 translocation in 96% of patients and PCR in 59% of patients. FISH was able to detect variant translocations involving light chain Ig, or showing variant patterns such as deletions of the IgH portion involved in translocation. In 4% of cases, the IgH/BCL2 translocation was not detected by any of the two techniques tested. Our results show that FISH represents the best technique to detect t(14;18) at diagnosis.