Frequencies of BCL2 and BCL6 translocations in representative Chinese follicular lymphoma patients: morphologic, immunohistochemical, and FISH analyses.

Abstract

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, which is the molecular hallmark of FL, whereas a subset of cases harbor translocations involving the BCL6 gene locus. To date, there has been no integrated analysis based on grade, phenotype, and genotype from large numbers of FL cases in a representative Chinese population. In this study, we graded 98 FL cases; fluorescence in situ hybridization was used to determine the BCL2 and BCL6 translocation statuses, and these were compared with morphologic and immunohistochemical parameters. The expressions of the 4 antigens were B-cell leukemia/lymphoma (BCL)-2(88.8%), BCL-6(80.6%), CD10(62.2%), and Ki67(50.0%), respectively. The frequencies of BCL2 and BCL6 translocations were 58.5% and 16.3%. In conclusion, the incidence of IgH/BCL2-positive FL in Chinese patients is relatively lower compared with that in western countries. BCL2 translocation strongly correlated with CD10 and Ki67 expression. Our data confirm the presence of a relationship between the translocation status and the FL histologic grade. All BCL6 translocations occurred in high-grade FL, and this suggests that FL carrying BCL6 translocation probably constitute a special biological subtype.