Characteristics of lymphoproliferative disorders with more than one aberrant cell population as detected by 10-color flow cytometry.

Background We have evaluated the frequency of lymphoproliferative disorders with more than one aberrant population of monotypic B-cells detected during routine hematopathological diagnostics. Materials and Methods 2600 samples peripheral (blood, bone marrow, fine-needle aspirate, lymph node, and pleural fluid cell suspensions) were analyzed using a 10-color B-cell panel and a 10-color T-cell panel. A 10-color plasma cell/lymphoplasmacytic panel was performed when appropriate. Results 790/2600 samples (30%) showed at least one aberrant B-cell population and 27(1%) showed an aberrant T-cell population. 41/790 samples (5.1%) showed two aberrant B-cell populations. Thirteen patients had two B-cell populations with different surface immunoglobulin restriction (one kappa+ and one lambda+), most with B-cell chronic lymphocytic leukemia-related phenotype. Five cases showed two B-cell populations with the same light chain restriction but distinctly different immunophenotypes. In 23 cases, two populations had the same light chain restriction and differed by expression of one or 2 markers, thus, a possibility of intraclonal differentiation could not be excluded. Cases with possible intraclonal differentiation had a significantly higher proportion of aberrant B-cells than those with two coexisting aberrant B-cell populations (49.9% vs. 27.7%, p = 0.008). In only one sample one population of clonal B-cell and one clonal T-cell population with large granular lymphocyte related phenotype were found. Conclusion Using our panels 5.1% of cases with lymphoproliferative disorder-associated aberrant findings show two aberrant (clonal) lymphoid and/or plasma cell populations. © 2016 International Clinical Cytometry Society