Abstract
There are three different marginal zone lymphomas (MZLs): the extranodal MZL of mucosa-associated lymphoid tissue (MALT) type (MALT lymphoma), the splenic MZL, and the nodal MZL. The three MZLs share common lesions and deregulated pathways but also present specific alterations that can be used for their differential diagnosis. Although trisomies of chromosomes 3 and 18, deletions at 6q23, deregulation of nuclear factor kappa B, and chromatin remodeling genes are frequent events in all of them, the three MZLs differ in the presence of recurrent translocations, mutations affecting the NOTCH pathway, and the transcription factor Kruppel like factor 2 ( KLF2) or the receptor-type protein tyrosine phosphatase delta ( PTPRD). Since a better understanding of the molecular events underlying each subtype may have practical relevance, this review summarizes the most recent and main advances in our understanding of the genetics and biology of MZLs.
Highlights
In the World Health Organization classification, there are three different marginal zone lymphoma (MZL) entities with specific diagnostic criteria, behavior, and therapeutic implications: the extranodal marginal zone lymphomas (MZLs) of mucosa-associated lymphoid tissue (MALT) type (MALT lymphoma), the splenic MZL (SMZL), and the nodal MZL (NMZL)[1]
MZLs are believed to derive from B cells of the “marginal zone”, the external part of the secondary lymphoid follicles
The three MZLs clearly share common lesions and deregulated pathways, but they present specific alterations that can be used for their differential diagnosis[5,6,7,8,9,10,11,12,13,14,15,16,17,18,19,20,21,22,23,24] (Figure 1)
Summary
In the World Health Organization classification, there are three different marginal zone lymphoma (MZL) entities with specific diagnostic criteria, behavior, and therapeutic implications: the extranodal MZL of mucosa-associated lymphoid tissue (MALT) type (MALT lymphoma), the splenic MZL (SMZL), and the nodal MZL (NMZL)[1]. Unlike the vast majority of other B-cell lymphomas, SMZL and NMZL do not present specific recurrent chromosomal translocations, while these are detected in MALT lymphomas, in which at least three of them activate the NF-κB pathway[8,9,10,11,12,13,14,16,34,35] (Figure 1). SMZL and NMZL present recurrent mutations of the BIRC3 gene in about 10% and 5% of cases, respectively[6,31,52] These mutations disrupt the same RING domain that is removed by the t(11;18) in MALT lymphomas, and the mutated BIRC3 is no longer able to inactivate MAP3K14 via ubiquitination[31,53]. NOTCH2 mutations are highly specific for SMZL and NMZL among mature B-cell tumors, including conditions that look alike, representing a biomarker with positive predictive value for non-MALT MZL specification. Grant information The author(s) declared that no grants were involved in supporting this work
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