Mutual exclusion of t(11;18)(q21;q21) and numerical chromosomal aberrations in the development of different types of primary gastric lymphomas.

Gastric non-Hodgkin's lymphomas can be divided histologically into mucosa-associated lymphoid tissue (MALT) lymphoma (ML) and diffuse large cell lymphoma (DLCL) with or without evidence of preceding/accompanying ML (DLCL + ML). We studied the incidence of the most frequent structural chromosomal aberration in ML, t(11;18)(q21;q21), and numerical aberrations of seven chromosomes in 36 ML, 39 DLCL + ML and ten gastric DLCL cases, by dual-colour interphase fluorescence in situ hybridization (FISH) and reverse transcriptase polymerase chain reaction (RT-PCR). t(11;18)(q21;q21) was exclusively detected in ML (FISH 22%; RT-PCR 24%), being completely absent in DLCL + ML and DLCL.