Betty Li

CD200 Flow Cytometric Assessment and Semiquantitative Immunohistochemical Staining Distinguishes Hairy Cell Leukemia From Hairy Cell Leukemia-Variant and Other B-Cell Lymphoproliferative Disorders

OBJECTIVESnTo evaluate CD200 expression in B-cell proliferative disorders.nnnMETHODSnWe analyzed 180 recent specimens of B-cell neoplasms for CD200 expression by flow cytometric immunophenotypic analysis, which is better able to assess relative intensity of staining than immunohistochemical staining.nnnRESULTSnWe found that hairy cell leukemia exhibits a high level of staining for CD200 in comparison to other B-cell lymphoproliferative disorders, including hairy cell leukemia-variant (HCL-V), marginal zone lymphoma, and lymphoplasmacytic lymphoma. We confirmed this observation by semiquantitative immunohistochemical staining.nnnCONCLUSIONSnAssessment of the CD200 expression level is helpful to distinguish HCL from HCL-V and other B-cell lymphoproliferative disorders and in the differential diagnosis of B-cell neoplasms in general.

Single Tube, Six-Color Flow Cytometric Analysis Is a Sensitive and Cost-Effective Technique for Assaying Clonal Plasma Cells

Bone marrow flow cytometric analysis is a powerful and rapid tool for evaluating plasma cell myeloma. By using a noncontrolled patient population in various stages of diagnosis and treatment, we compared 6-color (single-tube) and 4-color (multiple-tube) flow cytometric immunophenotyping protocols. Prospective comparison in 52 cases demonstrated improved ability to detect clonal plasma cells or identical diagnoses in 100% of the cases using 6-color, single-tube analysis. In cases in which 6-color flow cytometric analysis improved detection of a clonal population, concurrent biopsy showed less than 5% involvement by plasma cell myeloma, suggesting that 6-color flow cytometry has an advantage in patients with a low disease burden. In addition, the simplification of the procedure resulted in substantial savings in technologist time and reagent costs. Taken together, this study demonstrates that 6-color flow cytometry is an excellent, cost-effective means to assay for clonal plasma cells in a noncontrolled patient population.

High-Sensitivity Flow Cytometric Analysis for the Evaluation of Systemic Mastocytosis Including the Identification of a New Flow Cytometric Criterion for Bone Marrow Involvement

We used high-sensitivity flow cytometry to assess 93 bone marrow aspirates for involvement by systemic mastocytosis. Aberrant CD2/CD25 expression by CD117-gated mast cells was seen in 34 samples (37%), with the majority of mast cells expressing both markers (n = 23; 68%). In 24 cases, a discrete population of mast cells within the CD117-bright gate correlated with a positive morphologic finding in the biopsy, even in the absence of an aberrant immunophenotype. A discrete CD117-bright population, when considered a positive criterion, increases analytic sensitivity from 77% to 95%, exceeding the sensitivity of morphologic analysis (69% for aspirate and 85% for biopsy). We conclude that flow cytometry is a sensitive and specific test for the presence of systemic mastocytosis, particularly when the presence of a discrete CD117-positive mast cell population is regarded as a diagnostic criterion.

Patterns of expression of CD56 and CD117 on neoplastic plasma cells and association with genetically distinct subtypes of plasma cell myeloma

Abstract Plasma cell neoplasms are common hematopoietic malignancies that recently have been shown to be driven by specific genetic events. In the past decade, immunophenotyping by flow cytometry has become an important tool in the characterization of plasma cells. However, the clinical and prognostic significance of antigenic expression remains unclear. We analyzed 102 cases of plasma cell neoplasm by flow cytometric immunophenotyping for expression of CD56 and CD117 and correlated the results with immunohistochemical and cytogenetic findings. Expression of CD56 and CD117 was associated with hyperdiploidy and the absence of CD117 expression was associated with different immunoglobulin heavy chain gene (IGH) translocations. Assessment of CD117 expression on neoplastic plasma cells by flow cytometry is superior to immunohistochemistry. Simultaneous assessment of CD56 and CD117 expression by flow cytometry is a sensitive method for diagnostic evaluation of plasma cell neoplasms, and furthermore may function as a rapid adjunctive test providing independent prognostic information in the absence of cytogenetic data.

High-sensitivity flow cytometric analysis of mast cell clustering in systemic mastocytosis: a quantitative and statistical analysis

Abstract We characterized recently identified event clusters in systemic mastocytosis (SM) by calculating the coefficient of variation (CV, %) of CD117 and side scatter (SSC), based on the mean fluorescence intensity of mast cells using flow cytometry. Seventy-five samples were from patients with SM and 124 samples from patients negative for SM (non-SM). Discrete cluster formation seen in 50 cases correlated with significantly lower CV for SSC (46.1% vs. 61.0%, p < 0.0001) and CD117 (64.5% vs. 80.5%, p < 0.0001) for SM vs. non-SM samples. A combined CVCD117 + SSC of < 125 showed a sensitivity of 80% and specificity of 80% for SM with PPV of 67% and NPV of 80%. Probability scores of having SM, generated based on CVs for SSC and CD117, were significantly higher in patients with SM than non-SM (0.55 vs. 0.17, respectively; p < 0.001). Flow cytometric-based quantitative analysis of event clustering is a useful approach for diagnosing and monitoring patients with SM.

FLOCK Cluster Analysis of Mast Cell Event Clustering by High-Sensitivity Flow Cytometry Predicts Systemic Mastocytosis

OBJECTIVESnIn our high-sensitivity flow cytometric approach for systemic mastocytosis (SM), we identified mast cell event clustering as a new diagnostic criterion for the disease.nnnMETHODSnTo objectively characterize mast cell gated event distributions, we performed cluster analysis using FLOCK, a computational approach to identify cell subsets in multidimensional flow cytometry data in an unbiased, automated fashion.nnnRESULTSnFLOCK identified discrete mast cell populations in most cases of SM (56/75 [75%]) but only a minority of non-SM cases (17/124 [14%]). FLOCK-identified mast cell populations accounted for 2.46% of total cells on average in SM cases and 0.09% of total cells on average in non-SM cases (P < .0001) and were predictive of SM, with a sensitivity of 75%, a specificity of 86%, a positive predictive value of 76%, and a negative predictive value of 85%.nnnCONCLUSIONSnFLOCK analysis provides useful diagnostic information for evaluating patients with suspected SM, and may be useful for the analysis of other hematopoietic neoplasms.

Assessment of myeloid and monocytic dysplasia by flow cytometry in de novo AML helps define an AML with myelodysplasia-related changes category

Aims In recent years, multiparameter flow cytometry has been increasingly recognised as an important tool in diagnosis of myelodysplastic syndrome and acute myeloid leukaemia (AML). Assessment of myeloid and monocytic ‘immunophenotypic’ dysplasia by flow cytometry in de novo AML has not been evaluated. Methods 97 cases of de novo AML cases were identified and reviewed by three hematopathologists. ‘Immunophenotypic’ dysplasia was assessed on blasts, monocytes and granulocytes by mean fluorescence intensity. Results Using the 2008 WHO classification criteria, there were 53 AML-not otherwise specified (NOS) (55%) and 28 AML with myelodysplasia-related changes (AML-MRC) (29%), while 16 cases were ambiguous as to AML-MRC status due to limited maturing cells for morphologic but adequate events number for immunophenotypic evaluation (AML-not evaluable, 16%). Compared with AML-NOS, granulocytic cells in AML-MRC had higher CD33 expression but lower CD45, CD11b and CD15. Monocytes in AML-MRC had lower expression of CD14, CD56 and CD45. Morphologic dysplasia was associated with significantly lower granulocytic forward scatter, side scatter and CD10 but higher CD33 expression. Conclusions Our results suggest that the workup of AML cases should include flow cytometric assessment of granulocytes and monocytes. This analysis can aid a morphologic impression of multilineage dysplasia in distinguishing AML-MRC from AML-NOS, especially in cases with limited maturing myeloid cells.

FLOCK cluster analysis of plasma cell flow cytometry data predicts bone marrow involvement by plasma cell neoplasia

We analyzed plasma cell populations in bone marrow samples from 353 patients with possible bone marrow involvement by a plasma cell neoplasm, using FLOCK (FLOw Clustering without K), an unbiased, automated, computational approach to identify cell subsets in multidimensional flow cytometry data. FLOCK identified discrete plasma cell populations in the majority of bone marrow specimens found by standard histologic and immunophenotypic criteria to be involved by a plasma cell neoplasm (202/208 cases; 97%), including 34 cases that were negative by standard flow cytometric analysis that included clonality assessment. FLOCK identified discrete plasma cell populations in only a minority of cases negative for involvement by a plasma cell neoplasm by standard histologic and immunophenotypic criteria (38/145 cases; 26%). Interestingly, 55% of the cases negative by standard analysis, but containing a FLOCK-identified discrete plasma cell population, were positive for monoclonal gammopathy by serum protein electrophoresis and immunofixation. FLOCK-identified and quantitated plasma cell populations accounted for 3.05% of total cells on average in cases positive for involvement by a plasma cell neoplasm by standard histologic and immunophenotypic criteria, and 0.27% of total cells on average in cases negative for involvement by a plasma cell neoplasm by standard histologic and immunophenotypic criteria (p<0.0001; area under the curve by ROC analysis=0.96). The presence of a FLOCK-identified discrete plasma cell population was predictive of the presence of plasma cell neoplasia with a sensitivity of 97%, compared with only 81% for standard flow cytometric analysis, and had specificity of 74%, PPV of 84% and NPV of 95%. FLOCK analysis, which has been shown to provide useful diagnostic information for evaluating patients with suspected systemic mastocytosis, is able to identify neoplastic plasma cell populations analyzed by flow cytometry, and may be helpful in the diagnostic evaluation of bone marrow samples for involvement by plasma cell neoplasia.

Antigen expression patterns of MYC-rearranged versus non-MYC-rearranged B-cell lymphomas by flow cytometry

Abstract B-cell lymphomas with MYC rearrangement are a heterogeneous and unique group of neoplasms that may behave aggressively, especially in conjunction with other oncogenic alterations that cooperate with MYC, warranting early and intensive treatment in a subset of patients. Identification of MYC-rearranged B-cell lymphomas by immunophenotypic analysis could help guide cytogenetic work-up, as well as expedite therapeutic interventions. Using flow cytometry we analyzed the expression of CD10, CD19, CD20, CD38 and CD45 in 53 patients with three distinct neoplasms with MYC rearrangements: Burkitt lymphoma (n = 12), double hit lymphoma (n = 17) and diffuse large B-cell lymphoma (DLBCL) with MYC rearrangement (n = 8). The expression profile of these commonly used antibodies was similar among these three groups. The antigenic pattern of bright CD38 and dim CD45 was unique to the MYC-rearranged neoplasms when compared to non-MYC-rearranged aggressive DLBCL (n = 16), with a combined sensitivity of 67% and specificity of 100%, suggesting a shared underlying biology among these MYC rearranged B-cell lymphomas.

Flow cytometric minimal residual disease assessment of peripheral blood in acute lymphoblastic leukaemia patients has potential for early detection of relapsed extramedullary disease

Objectives To evaluate peripheral blood (PB) for minimal residual disease (MRD) assessment in adults with acute lymphoblastic leukaemia (ALL). Methods We analysed 76 matched bone marrow (BM) aspirate and PB specimens independently for the presence of ALL MRD by six-colour flow cytometry (FC). Results The overall rate of BM MRD-positivity was 24% (18/76) and PB was also MRD-positive in 22% (4/18) of BM-positive cases. We identified two cases with evidence of leukaemic cells in PB at the time of the extramedullary relapse that were interpreted as MRD-negative in BM. Conclusions The use of PB MRD as a non-invasive method for monitoring of systemic relapse may have added clinical and diagnostic value in patients with high risk of extramedullary disease.