Background and objectives: Salivary gland mucosa-associated lymphoid tissue (MALT) lymphomas typically lack chromosomal translocations and the molecular genetics underlying their development is unknown. The aim of this sudy was to investigate chromosomal changes in these lymphomas.
Design and methods: We performed comparative genomic hybridisation using DNA samples extracted from microdissected tumour cells in 19 salivary gland MALT lymphomas. Recurrent chromosomal changes were further verified by interphase fluorescence in situ hybridization (FISH).
Results: Chromosomal gains were much more common than losses. Recurrent gains were found at 1p32-ter (42%), 9q33-34 (84%), 11q11-13 (42%), 17 (58%) and 18q21-22 (42%). Among these, the recurrent gains at 9q34, 11q11-13 and 18q21 were nearly the exclusive gain of the corresponding chromosome. Notably, chromosomal gains at 9q34, 11q13 and 18q21 were frequently concurrent, with 12/19 cases affecting at least two of the three loci. The genomic gains at these chromosomal regions were further confirmed by interphase FISH with probes targeting the TRAF2 and CARD9 (9q34), RELA and CCND1 (11q13), and MALT1 (18q21) loci.
Interpretation and conclusions: Salivary gland MALT lymphomas show a conserved pattern of chromosomal gains, which appear to target genes positively modulating cell survival and proliferation.