Analysis of follicular lymphoma by dual-color fluorescence in situ hybridization.

Follicular lymphoma (FL) is divided into two groups: one with the t(14;18)(q32;q21) and the other without this translocation but with other chromosomal abnormalities including t(3q27) break. The majority of FLs in Western countries have the former chromosomal changes with characteristic clinical features and low histological grades. The goal of this study was to investigate the characteristics of Korean FLs with regard to the underlying molecular defects. Sixty-one cases of FL were evaluated from two centers in Korea by immunostaining for CD10, bcl-2, and bcl-6 proteins. Fluorescence in situ hybridization was performed to detect the t(14;18) and t(3q27) break. Cases with FL grade 3 accounted for 57% of all 61 cases. The t(14;18) was detected in 43.9% of the cases studied, and the frequency was 80, 50, 34.8, and 9.1% from grade 1 through grade 3b. The t(3q27) was detected in 16.1% of cases. Cases without a t(14;18) were mainly histological grade 3 (P < 0.001) and had a tendency to have the t(3q27) and bcl-2 amplification. The incidence of t(14;18)-positive low-grade FL was found to be lower in Korea than in Western countries. The increased frequency of t(14;18)-negative grade 3 FL attributes to the lower incidence of t(14;18) in Korean FL.