title: Nodal reactive and neoplastic proliferation of monocytoid and marginal zone B cells: an immunoarchitectural and molecular study highlighting the relevance of IRTA1 and T-bet as positive markers.
abstract: OBJECTIVE
  Marginal zone B cells (MZCs) and monocytoid B cells (MBCs) appear to be related lymphoid cells that take part in reactive and neoplastic marginal zone proliferations. These lesions are not yet well characterized, and the aim of this study was to find better diagnostic criteria for them.
  
  
  RESULTS
  We analysed 60 nodal lesions with MBC and/or MZC proliferation for their morphological, immunophenotypic, molecular genetic and IG gene rearrangement features. On the basis of the results of the rearrangement assay and immunoglobulin light chain restriction, the lesions were divided into reactive and neoplastic groups. Among the neoplastic lesions, polymorphic and monomorphic subgroups emerged. All reactive lesions had morphological features of the polymorphic subgroup. By immunohistochemistry, IRTA1 and/or T-bet expression was found in all reactive lesions and in 90% of neoplastic lesions.
  
  
  CONCLUSIONS
  IRTA1 and T-bet are positive markers for the identification of MZC/MBC proliferations, and thus for the diagnosis of nodal marginal zone lymphoma (NMZL). Polymorphic and monomorphic subgroups of NMZL could be distinguished. Most morphological and immunophenotypic patterns in reactive and neoplastic nodal expansions of MZCs and MBCs overlapped. Therefore, PCR clonality assay of the immunoglobulin heavy and light chain gene loci is the most reliable method for their differentiation.
authors.affiliation: Pathodiagnostik Berlin, Berlin Reference and Consultation Centre for Lymphoma and Haematopathology, Berlin, Germany; Institute for Pathology, Campus Benjamin Franklin, Charite Universitätsmedizin Berlin, Berlin, Germany.
authors.forename: Roshanak
authors.initials: R
authors.lastname: Bob
authors.forename: Brunangelo
authors.initials: B
authors.lastname: Falini
authors.forename: Teresa
authors.initials: T
authors.lastname: Marafioti
authors.forename: Jennifer C
authors.initials: JC
authors.lastname: Paterson
authors.forename: Stefano
authors.initials: S
authors.lastname: Pileri
authors.forename: Harald
authors.initials: H
authors.lastname: Stein
mesh_terms: D000328:Adult; D000368:Aged; D000369:Aged, 80 and over; D001402:B-Lymphocytes / Q000378:metabolism / Q000473:pathology*; D014408:Biomarkers, Tumor / Q000032:analysis*; D049109:Cell Proliferation; D005260:Female; D006801:Humans; D007150:Immunohistochemistry; D016130:Immunophenotyping; D017404:In Situ Hybridization, Fluorescence; D008198:Lymph Nodes / Q000473:pathology; D018442:Lymphoma, B-Cell, Marginal Zone / Q000175:diagnosis* / Q000378:metabolism; D008297:Male; D008875:Middle Aged; D016133:Polymerase Chain Reaction; D011961:Receptors, Fc / Q000032:analysis / Q000096:biosynthesis*; D020825:T-Box Domain Proteins / Q000032:analysis / Q000096:biosynthesis*; D000098815:T-bet Transcription Factor
chemical_list: D014408:Biomarkers, Tumor; C423544:FCRL4 protein, human; D011961:Receptors, Fc; D020825:T-Box Domain Proteins; D000098815:T-bet Transcription Factor
keywords: IRTA1/MUM2; T-bet; marginal zone expansion; monocytoid B cells; nodal marginal zone lymphoma