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 regularlypresents with peripheral blood (PB) involvement. A precise description of clinical, laboratoryfeatures and immunophenotypic characterization of SMZL are still lacking. Here, we reviewed34 patients presenting with SMZL to describe the clinical, hematologic features, and flow cytometryimmunophenotypic findings of this type of lymphoma at diagnosis.OBJECTIVES: The aim of this study is to confirm that SMZL has a specific immunologic profile whichenables the hematopathologist and clinician to differentiate this low‑grade B‑cell lymphoma from otherB‑cell lymphoproliferative disorder, especially chronic lymphocytic leukemia and hairy cell leukemia,which could sometimes stimulate SMZL morphologically and to emphasize that a correlation ofimmunophenotypic findings, clinical, and hematologic features of patients plus careful morphologicalexamination 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 werereviewed. 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 markerwas 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. Allpatients presented with splenomegaly, 71% of patients had absolute lymphocytosis and 88% ofpatients showed PB involvement. Seventy‑four percent of patients had anemia and (53%) of themhad thrombocytopenia. Cells from all cases expressed pan B‑cell antigens (CD19, CD20), 74% ofcases expressed CD79b and Human Leukocyte Antigen – antigen D Related (HLA-DR) expressedin nearly almost all cases (97%). Half of the patients expressed CD11c and SIgD, 41% expressedCD5 and FMC7 while CD25 and CD103 showed positivity in less than 5% of cases. Preferentialexpression of Kappa light chain was demonstrated, CD10 and CD38, SIgG were negative.CONCLUSION: SMZL has a distinct immunologic profile which if correlated with morphologic findingsof PB or BM aspirates, clinical and hematologic features can help to make the accurate diagnosisand lessens the need of further invasive diagnostic procedure.