Primary cutaneous marginal zone B-cell lymphoma may exhibit both the t(14;18)(q32;q21) IGH/BCL2 and the t(14;18)(q32;q21) IGH/MALT1 translocation: an indicator for clonal transformation towards higher-grade B-cell lymphoma?

Primary cutaneous marginal zone B-cell lymphoma (PCMZL) is a recently proposed entity and constitutes the cutaneous counterpart of extranodal marginal zone B-cell lymphoma of mucosa-associated lymphoid tissue (MALT). The t(14;18)(q32;q21) involving the IGH and the MALT1 gene has previously been described in PCMZL, whereas the t(14;18)(q32;q21) IGH/BCL2 seems to be restricted to follicular lymphoma and diffuse large B-cell lymphoma. We screened 30 PCMZLs of 13 patients by fluorescent in situ hybridization analysis for the presence of the t(14;18)(q32;q21) IGH/BCL2 and the t(14;18)(q32;q21)IGH/MALT1. The t(14;18)(q32;q21) IGH/MALT1 was detected in 10 PCMZLs of eight patients, with four patients showing the t(14;18)(q32;q21) IGH/MALT1 exclusively. The t(14;18)(q32;q21)IGH/BCL2 was detected in 16 PCMZLs of seven patients, with four patients showing the t(14;18)(q32;q21) IGH/BCL2 exclusively. Six lymphomas of four patients showed both translocations in the same lesion. In seven lymphomas, neither of the two translocations occurred. One patient developed multiple lesions without either of the two translocations. Our results underline that both the t(14;18)(q32;q21)IGH/BCL2 and the t(14;18)(q32;q21) IGH/MALT1 may occur in PCMZL, albeit in an irregular distribution. Therefore, the etiopathogenetic relevance of either translocation in PCMZL remains a matter of debate.