Chromosomal analyses of 52 cases of follicular lymphoma with t(14;18), including blastic/blastoid variant

Abstract

We have identified 52 patients of follicular lymphoma (FL) with t(14;18)(q32;q21). Histologically, the lymphomas were placed into six groups according to their cellular composition and growth pattern. Chromosome analysis revealed that all cases but one had additional secondary chromosomal abnormalities. The most frequent numerical aberrations were gains of chromosomes 7 (38%), X (36%), 5 (15%), 12 (15%), 18/der(18)t(14;18) (25%), and 21 (15%). Structural abnormalities of chromosome 1 were seen in 19 tumors (36%) affecting both arms with breakpoints clustered at 1p36. Other structural abnormalities included partial deletions of 6q, 10q, and 13q. Breakpoint at 8q24 was seen in four cases. The chromosome aberrations were correlated with the morphological subtypes of follicular lymphoma. Gain of chromosome 7 appeared to be associated with follicular large cell lymphoma. The incidence of trisomy 5 and 12, and 13q- was higher in follicular lymphoma with aggressive histological features than in low-grade lymphoma. In addition, complexity of the karyotype and high degree of polyploidy increased with the grade. The most valuable cytogenetic markers in the t(14;18) lymphomas are those involving 8q24 which was found exclusively in the blastic/blastoid variant FL. Therefore, chromosome analysis in relation to histologic pattern of follicular lymphoma can provide additional information in predicting tumor evolution and transformation to a higher-grade malignancy.