The product of the t(11;18), an API2–MLT fusion, is an almost exclusive finding in marginal zone cell lymphoma of extranodal MALT-type

1569-8041

API2–MLT ; marginal zone cell lymphoma ; RT–PCR

Springer Online Journal Archives 1860-2000

Medicine

Abstract Background:Extranodal marginal zone cell lymphoma (MZCL) ofMALT-type share similar features with nodal and splenic MZCL regardingmorphology and immunophenotype. At the genetic level, recent cytogeneticstudies have shown that t(11;18) is a recurring abnormality in extranodalMALT-type MZCL but has hitherto never been reported in nodal or splenic MZCL.The aim of the present study was to determine the prevalence of t(11;18) ina large series of nodal, splenic and extranodal MALT-type MZCL, using asensitive real-time RT–PCR method. Materials and methods:Ninety-three MZCL cases were divided onclinical grounds into 61 extranodal MALT-type, 19 splenic and 12 nodal MZCL.One case that presented with a massive splenomegaly but for which alsogastro-intestinal localisations were found, was left unclassified. A real-timeRT–PCR method for the detection of the API2–MLT fusion resulting from t(11;18) was performed on RNA extracted from frozen tissuesections. Results:The API2–MLT fusion was detected in 12cases, which were all extranodal MALT-type lymphomas of the stomach, exceptfor one case. The remaining positive case was the unclassified case, for whichthe translocation was detected in the spleen and in hilar lymph node tissue. Conclusions:While similarities between MZCL from differentanatomic sites have lend us to propose that all MZCL have a common normalcounterpart, the almost exclusive detection of t(11;18) in gastric MALT-typelymphoma favours its recognition as a separate lymphoma entity. The absenceof the translocation in nodal and splenic MZCL challenges the idea of theselymphomas being secondary to MALT-type lymphomas of the gut. The unclassifiedcase illustrates the inadequate approaches available at present to identifyand define the various MZCL.

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