Analysis of secondary chromosomal alterations in 165 cases of follicular lymphoma with t(14;18)

Follicular lymphoma is characterized by the t(14;18) in up to 85% of cases. Almost all cases display evidence of secondary chromosomal alterations at initial diagnosis. The influence of recurrent secondary changes on disease progression has not been fully determined. The purpose of this study was to define the full spectrum of recurrent karyotypic events present at diagnos is in a large cohort of cases and to evaluate the sequence of cytogenetic e volution in relation to morphologic progression. A total of 165 cases of fo llicular lymphoma with t(14;18) were ascertained for which complete clinica l information, histopathology, immunophenotype, and karyotype were availabl e. One hundred sixty cases showed secondary alterations with an average of 7.9 additional changes per case. Recurrent alterations seen at the 10% or g reater level included +X, + 1q21-q44, +7, + 12q, + 18q, del(1)(p36), del(6q ), del(10)(q22-q24), the development of polyploidy and sidelines, and the p resence of extra marker chromosomes and chromosomal additions. Changes that correlated with morphologic progression included del(1)(p36), del(6q), del (10)(q22-q24), +7, the total number of abnormalities. the number of markers and additions, and the presence of polyploidy. The most frequent second ev ent arising after the t(14;18) was duplication of the der(18)t(14;18). This study demonstrates thar the number and type of secondary chromosomal alter ations in follicular lymphoma is highly variable between cases, but that a relatively small number of changes are seen repeatedly in different combina tions. A consistent pattern of cytogenetic evolution could not be identifie d. Potentially significant gene duplications or amplifications may be disgu ised within marker chromosomes and additions. Additional cytogenetic invest igation is required to decipher the karyotypic complexity associated with t he progression of follicular lymphoma, (C) 2001 Wiley-Liss, Inc.