The t(14;18)(q32;q21)/IGH-MALT1 translocation in gastrointestinal extranodal marginal zone lymphoma of mucosa-associated lymphoid tissue (MALT lymphoma).

Aims Studies have indicated that the t(14;18)(q32;q21)/IGH-MALT1 translocation is present in extranodal marginal zone lymphomas of mucosa-associated lymphoid tissue (MALT lymphoma). However, only a few studies have investigated the incidence of t(14;18)/IGH-MALT1 in primary gastrointestinal MALT lymphomas or in diffuse large B-cell lymphomas (DLBCL). The overall significance of t(14;18)/IGH-MALT1 in gastrointestinal MALT lymphomas is not clear. We examined 41 gastrointestinal MALT lymphoma and 23 DLBCL cases, with the aim of further understanding the role of t(14;18)/IGH-MALT1 in these diseases. Methods and results Fluorescence in-situ hybridization (FISH) assays for the detection of t(14;18)/IGH-MALT1 and t(11;18)(q21;q21)/API2-MALT1, along with immunostaining and histological evaluations, were performed on selected cases. Of the 64 analysed cases, one gastric MALT lymphoma and one colonic MALT lymphoma were positive for t(14;18)/IGH-MALT1. Conclusions We describe what are, to our knowledge, the first reported primary colonic MALT lymphoma carrying t(14;18)(q32;q21)/IGH-MALT1, and one of the few reported cases of gastric MALT lymphoma with this translocation. As this translocation is seen in only a few gastrointestinal MALT lymphomas, it is not useful as a diagnostic marker for routine clinical services. Although these findings suggest that t(14;18)/IGH-MALT1 is a rare molecular event in gastrointestinal MALT lymphomas and DLBCLs, further studies to elucidate the role of this genetic alteration in these diseases are indicated.