The complex pathology and differential diagnosis of splenic and nodal marginal zone lymphoma

Abstract

Marginal zone lymphoma is a term applied to different B-cell low-grade lymphoma disorders with some common features, originated around reactive follicles, composed by small/medium size cells with specific immunophenotype, Ig genes stereotypes and somatic mutation of genes (NOTCH2, KLF2, TNFAIP3...) involved in marginal zone differentiation and NF-kB activation. Marginal zone lymphoma differential diagnosis is based on an integration of clinical, morphological and molecular features. Here we describe the current status of splenic and nodal marginal zone lymphoma (NMZL) diagnosis, reviewing also the markers (MNDA, T-Bet, IRTA1) that facilitate their recognition and diagnosis. Splenic marginal zone lymphoma (SMZL) is a disseminated lymphoma since the initial diagnosis, with both bone marrow and peripheral blood infiltration at diagnosis in almost every case. In contrast, NMZL is frequently a tumor restricted to lymph nodes, where bone marrow and/or peripheral blood involvement is only seen ad advanced stages. Both SMZL and NMZL have a spectrum of clinical presentations ranging from subclinical monoclonal B-cell lymphocytosis at earlier stages to aggressive disorders in advanced stages where p53 mutations, increased CD30 expression or EBV presence are frequently detected.