Molecular-cytogenetic comparison of mucosa-associated marginal zone B-celllymphoma and large B-cell lymphoma arising in the gastro-intestinal tract

Extranodal B-cell lymphoma of mucosa-associated lymphoid tissue (MALT) type may represent a model of lymphoma progression, because a small cell compon ent frequently occurs in the large cell variants. We studied 52 extranodal B-cell lymphomas: 18 extranodal marginal zone B-cell lymphomas of MALT type (MZBL,MT), 7 MZBL,MT of the gastro-intestinal tract with a diffuse large B -cell component (giMZBLplusLBCL), and 27 diffuse large B-cell lymphomas of the gastro-intestinal tract without small cell component (giLBCL). Analytic al techniques were comparative genomic hybridization (CGH) and fluorescence in situ hybridization (FISH). The translocation t(11;18) was found as the sole aberration in two MZBL,MT only. In contrast to this, t(11;18)-negative MZBL,MT were characterized by frequent gains on chromosome 3 and DNA ampli fications on 2p 13-p 15. Furthermore, we found a clonal lymphoma progressio n from the small to the large cell component with accumulation of gains and losses of chromosomal material in the large cell component in giMZBLplusLB CL Aberrations overlapping with MZBL,MT and giMZBLplusLBCL included losses on chromosome 13, amplifications of the REL protooncogene, or gains on chro mosome 12. In addition, the large cell component revealed gains on 8q24, in cluding amplifications of the MYC proto-oncogene, and losses on 2q. The giL BCL had frequent gains on chromosomes 12 and 9, as well as on 11q, and loss es on 6q. We conclude that, based on the distinctive and partly overlapping patterns of genetic aberrations, MALT lymphomas can be divided into differ ent genetic subgroups. (C) 2001 Wiley-Liss, Inc.