Characteristics of splenic marginal zone lymphoma: Clinical, hematologic, and flow cytometry findings of 34 cases

Abstract

Background: Splenic marginal zone lymphoma (SMZL) is a low-grade disorder that regularly presents with peripheral blood (PB) involvement. A precise description of clinical, laboratory features and immunophenotypic characterization of SMZL are still lacking. Here, we reviewed 34 patients presenting with SMZL to describe the clinical, hematologic features, and flow cytometry immunophenotypic findings of this type of lymphoma at diagnosis. Objectives: The aim of this study is to confirm that SMZL has a specific immunologic profile which enables the hematopathologist and clinician to differentiate this low-grade B-cell lymphoma from other B-cell lymphoproliferative disorder, especially chronic lymphocytic leukemia and hairy cell leukemia, which could sometimes stimulate SMZL morphologically and to emphasize that a correlation of immunophenotypic findings, clinical, and hematologic features of patients plus careful morphological examination of PB and/or bone marrow (BM) aspirate can lead confidently to the correct diagnosis. Materials And Methods: Flow cytometry immunophenotypic findings of 34 cases of SMZL were reviewed. The analysis was performed by BD FACS Calibur™ and FACSCanto II flow cytometers. B lymphocytes were identified according to their Side-Scattered (SSC)/CD19 distribution. A marker was considered positive when expressed in more than 20% of cells above the control. Results: Median age was 60 years, range (35–84 years), both sexes were affected equally. All patients presented with splenomegaly, 71% of patients had absolute lymphocytosis and 88% of patients showed PB involvement. Seventy-four percent of patients had anemia and (53%) of them had thrombocytopenia. Cells from all cases expressed pan B-cell antigens (CD19, CD20), 74% of cases expressed CD79b and Human Leukocyte Antigen – antigen D Related (HLA-DR) expressed in nearly almost all cases (97%). Half of the patients expressed CD11c and SIgD, 41% expressed CD5 and FMC7 while CD25 and CD103 showed positivity in less than 5% of cases. Preferential expression of Kappa light chain was demonstrated, CD10 and CD38, SIgG were negative. Conclusion: SMZL has a distinct immunologic profile which if correlated with morphologic findings of PB or BM aspirates, clinical and hematologic features can help to make the accurate diagnosis and lessens the need of further invasive diagnostic procedure.

Keywords

• Clinical
• flow cytometer
• hematologic
• immunophenotyping
• multiparameter
• splenic marginal zone lymphoma