Fiona E. Craig

Primary effusion lymphoma (PEL) in patients with Human Immunodeficiency Virus (HIV) infection may involve pleural, pericardial, and peritoneal cavities. PEL involving the cerebrospinal fluid (CSF) is exceedingly rare, and to our knowledge has only been reported in two cases. We report another case of PEL diagnosed in CSF from a 61-year-old male with Acquired Immunodeficiency Syndrome that presented with neurological symptoms. Imaging studies of his brain showed leptomeningeal/periventricular enhancement, but no mass lesion. His CSF demonstrated human herpesvirus-8 positive pleomorphic lymphoplasmacytoid cells of null cell phenotype. This case highlights that albeit rare, PEL should be included in the differential diagnosis when large atypical cells are encountered in CSF of HIV-positive patients, even when such patients have no history of lymphoma. As in this case, ancillary studies are required to make an accurate diagnosis of PEL in CSF cytology.

The Case Study Interpretation (CSI) cases presented at the 2014 International Clinical Cytometry Society (ICCS) meeting in Seattle illustrate the utility of state‐of‐the art multiparameter flow cytometry in the diagnosis of hematolymphoid neoplasms. Download the listmode files (Supporting Information) and test your analysis skills before reading the case reports, keeping in mind the following questions. How many separate abnormal mature B‐cell populations can you identify, and how many of these represent different subtypes of B‐cell neoplasm? How many separate abnormal mature T‐cell populations can you identify, and do these represent different subtypes of T‐cell neoplasm or phenotypic heterogeneity in one neoplasm? How many separate immature/blastic cell populations can you identify, and do they meet criteria for mixed phenotype leukemia? Is there a population of blasts that lacks T‐cell, B‐cell, and myeloid lineage defining antigens and if so, what entities should you consider and what additional antigens should you assess for? © 2015 International Clinical Cytometry Society

Flow cytometry can assist in the diagnosis of lymphoma by identifying aberrant antigen expression. Recognition of aberrancy requires knowledge of the phenotype of normal lymphoid cells. Lymphoid subsets were characterized in 20 spleens removed for traumatic rupture, using 8-color flow cytometry. Normal variation in splenic lymphoid subsets was highlighted and several well-recognized subsets were identified: CD5+ B cells (20/20 specimens), CD7− T cells (20/20), and CD3 brightγδT cells (16/20). In addition, less well-recognized lymphoid subsets that resemble those described in lymphoma were identified in all specimens: CD5− T cells (4.5 ± 5.1% of T cells), CD2− natural killer (NK) cells (38 ± 7% of NK cells), and CD7dim+ NK cells. Similar populations were identified in 20 control peripheral blood specimens, where they represented a smaller proportion of total lymphoid cells. Familiarity with the phenotype of normal lymphoid subsets can help prevent misinterpreting flow cytometric data. Furthermore, in the context of neoplastic cells, the phenotype may suggest expanded normal subsets rather than aberrant antigen expression.

BackgroundAlthough many clinical laboratories are adopting higher color flow cytometric assays, the approach to optimizing panel design and data analysis is often traditional and subjective. In order to address the question What is the best flow cytometric strategy to reliably distinguish germinal center B-cell lymphoma (GC-L) from germinal center hyperplasia (GC-H)? we applied a computational tool that identifies target populations correlated with a desired outcome, in this case diagnosis. DesignCases of GC-H and GC-L evaluated by flow cytometric immunophenotyping using CD45, CD20, kappa, lambda, CD19, CD5, CD10, CD38, were analyzed with flowType and RchyOptimyx to construct cellular hierarchies that best distinguished the two diagnostic groups. ResultsThe population CD5-CD19+CD10+CD38- had the highest predictive power. Manual reanalysis confirmed significantly higher CD10+/CD38-B-cells in GC-L (median 12.44%, range 0.74-63.29, n=52) than GC-H (median 0.24%, 0.03-4.49, n=48, P=0.0001), but was not entirely specific. Difficulties encountered using this computational approach included the presence of CD10+ granulocytes, continuously variable B-cell expression of CD38, more variable intensity antigen staining in GC-L and inability to assess the contribution of light chain restriction. ConclusionComputational analysis with construction of cellular hierarchies related to diagnosis helped guide manual analysis of high dimensional flow cytometric data. This approach highlighted the diagnostic utility of CD38 expression in the evaluation of B-cells with a CD10+ GC phenotype. In contrast to computational analysis of non-neoplastic cell populations, evaluation of neoplastic cells must be able to take into consideration increased variability in antigen expression. (c) 2013 International Clinical Cytometry Society

Establishing the diagnosis of myelodysplastic syndrome (MDS) can be difficult and requires a multiparametric approach, with correlation of the clinical, morphologic and genetic features. Although M...

Background: Laboratories utilize diverse methods to determine the absolute count used to distinguish chronic lymphocytic leukemia (CLL) from monoclonal B lymphocytosis, with many using dual platform (DP) methods (flow cytometric percent of CLL‐like B cells × hematology analyzer white blood cell count). However, flow cytometric tube‐to‐tube variation may make interpretation difficult, particularly when the CLL‐like B‐cell count straddles the recommended threshold. This study investigates the extent, and potential sources, of this variability.Methods: Flow cytometric enumeration was performed on 20 samples with CLL‐like B cells and 10 control specimens using single platform (SP) and two DP tubes A: kappa, lambda, CD5, CD10, CD19, CD38, CD45, CD20 and B: FMC‐7, CD23, CD19, CD5, with and without racking to remove doublets. In addition, reproducibility studies were performed.Results: Three specimens showed discordant CLL‐like B‐cell counts relative to the threshold of 5 × 10⁹/L. Bland–Altman analysis demonstrated a systematic bias with DP Tube B > A (5.9%) and SP > DP Tube A (9.5%). The doublet percent varied between specimens, but did not account for the bias between DP tubes. Variation was also seen in enumeration of other cell types, suggesting multiple potential sources of inconsistency.Conclusions: Significant tube‐to‐tube variation may be seen in CLL‐like B‐cell counts. The precise cause of these differences is uncertain, but is likely multifactorial. If the clinical utility of an absolute threshold for the diagnosis of CLL can be confirmed, it will be important to establish recommendations for standardization, similar to those employed for CD4 and CD34 enumeration. © 2013 International Clinical Cytometry Society