Mucosa-associated lymphoid tissue (
MALT) lymphoma is a type of B-cell
non-Hodgkin lymphoma that can originate in the gastrointestinal (GI) tract, thyroid, breasts, lungs, and skin. The most common genetic abnormality occurring in
MALT lymphomas involves t(11;18)(q21;q21) in the gene MALT1. This translocation results in a chimeric fusion product between the genes ATI2 and MALT1, which generates a survival advantage in the
lymphoma cells. The MALT1 disruption is more common in some
MALT lymphomas, distinguished by site, than others. If identified, this variation in frequency could affect treatment courses and outcomes for each type of
MALT lymphoma. The study included 109
MALT lymphoma sample specimens. The sample
paraffin-embedded slides were pretreated, hybridized for FISH using a MALT1 break-apart probe, post-washed, and viewed using a fluorescent microscope. On each slide, 100 individual cells were counted by two independent readers, totaling 200 cells per case, and the percentage of cells containing a translocation within each sample was recorded. A conservative threshold of 8% was used to make a positive call. There were a total of 18 positive results in the 109 samples tested. The tissue specimens tested that yielded positive results include the colon (62.5%), lung (57.14%), skin (25%), eyelid/lacrimal gland (16.67%), stomach (6.45%), kidney (50%), and thyroid (100%). The sites that yielded only negative results (0%) include the breast, salivary gland, salivary gland/parotid, soft tissue/skin, conjunctiva/orbital, small intestine, nasal, and epidural mass. As hypothesized, a variation in the MALT1 disruption was found. This is the first study to examine MALT1 disruption in the soft tissue, nasal, and epidural mass. The positive results of this study, specifically the results for the colon and lung, and the negative breast and salivary gland results are consistent with previous studies examining the genetic aberrations in
MALT lymphomas. These results indicate that
MALT lymphoma at different locations differentially display MALT1 disruption, and these disruptions may be responsible for the variance in patient response to
therapy. Surgery,
radiation therapy, and/or administration of
cladribine (2CdA) result in the best outcomes in treating
MALT lymphomas with MALT1 disruption.