Diagnostic utility of flow cytometry in low-grade myelodysplastic syndromes: a prospective validation study

Standardization of flow cytometry in myelodysplastic syndromes: a report from an international consortium and the European LeukemiaNet Working Group

Flow cytometry (FC) is increasingly recognized as an important tool in the diagnosis and prognosis of myelodysplastic syndromes (MDS). However, validation of current assays and agreement upon the techniques are prerequisites for its widespread acceptance and application in clinical practice. Therefore, a working group was initiated (Amsterdam, 2008) to discuss and propose standards for FC in MDS. In 2009 and 2010, representatives from 23, mainly European, institutes participated in the second and third European LeukemiaNet (ELN) MDS workshops. In the present report, minimal requirements to analyze dysplasia are refined. The proposed core markers should enable a categorization of FC results in cytopenic patients as 'normal', 'suggestive of', or 'diagnostic of' MDS. An FC report should include a description of validated FC abnormalities such as aberrant marker expression on myeloid progenitors and, furthermore, dysgranulopoiesis and/or dysmonocytopoiesis, if at least two abnormalities are evidenced. The working group is dedicated to initiate further studies to establish robust diagnostic and prognostic FC panels in MDS. An ultimate goal is to refine and improve diagnosis and prognostic scoring systems. Finally, the working group stresses that FC should be part of an integrated diagnosis rather than a separate technique.

Role of flow cytometry in diagnostics of myelodysplastic syndromes--beyond the WHO 2008 classification

Multiparameter flow cytometry (FCM) is an excellent method to follow the expression patterns of differentiation antigens using monoclonal antibodies to surface and cytoplasmic proteins. Although several authors described various aberrant immunophenotypic features in the bone marrow of patients with myelodysplastic syndromes (MDS), the World Health Organization 2008 classification recommended that, only if 3 or more phenotypic abnormalities are found involving 1 or more of the myeloid lineages can the aberrant FCM findings be considered suggestive of MDS. In the absence of conclusive morphologic and/or cytogenetic features, FCM abnormalities alone were considered not sufficient to establish MDS diagnosis and further follow-up of the patients was recommended. Review of the literature gives accumulating evidence that FCM has become an important part of the integrated diagnostic work-up of patients with suspected MDS. Several studies have also reported FCM findings significant for prognosis and therapy choice in MDS patients. Technical progress in multicolor FCM and new analysis programs, together with ongoing efforts to standardize the methodology, will make it possible to apply FCM in individual risk assessment and choice of best therapy for MDS patients.

Implementation of flow cytometry in the diagnostic work-up of myelodysplastic syndromes in a multicenter approach: report from the Dutch Working Party on Flow Cytometry in MDS

Flow cytometry (FC) is recognized as an important tool in the diagnosis of myelodysplastic syndromes (MDS) especially when standard criteria fail. A working group within the Dutch Society of Cytometry aimed to implement FC in the diagnostic work-up of MDS. Hereto, guidelines for data acquisition, analysis and interpretation were formulated. Based on discussions on analyses of list mode data files and fresh MDS bone marrow samples and recent literature, the guidelines were modified. Over the years (2005-2011), the concordance between the participating centers increased indicating that the proposed guidelines contributed to a more objective, standardized FC analysis, thereby ratifying the implementation of FC in MDS.

Prognostic relevance of cytometric quantitative assessment in patients with myelodysplastic syndromes

OBJECTIVES

Morphology and cytogenetics are currently used to define prognosis in myelodysplastic syndromes (MDS). However, these parameters have some limits. Flow cytometry has been recently included in the diagnostic panel for MDS, and its prognostic significance is under evaluation.

METHODS

Marrow aspirates from 424 MDS patients were analyzed by flow cytometry to evaluate the impact of bone marrow cell immunophenotype on overall survival (OS) and leukemia-free survival (LFS). The immature compartment of myeloblasts was analyzed by the quantitative expression of CD34 (<3% vs. ≥3%), CD117, and CD11b(-) /CD66b(-) (<5% vs. ≥5%); myeloid maturation was analyzed by the expression of CD11b(+) /CD66b(++) (<15% vs. ≥15%) and CD11b(+) /CD66b(+) (<25% vs. ≥25%).

RESULTS

In univariate analysis, the expression of immaturity markers (CD34(+) , CD117(+) , and CD11b(-) /CD66b(-) ) was associated with shorter LFS and OS (P < 0.0001); higher expression of differentiation markers (CD11b(+) /CD66b(++) and CD11b(+) /CD66b(+) ) was associated with longer LFS (P < 0.0001 and P = 0.0002, respectively) and OS (P < 0.0001). In multivariate analysis, expression of CD34(+) (P = 0.007), CD117(+) (P = 0.013), and CD11b(+) /CD66b(++) (P = 0.023) retained independent prognostic value for OS, while only the expression of CD34(+) was a prognostic factor for LFS (P = 0.0003). Two different risk groups were defined according to the presence of 0-1 or ≥2 of these factors with significant different LFS and OS (P < 0.0001). This score showed prognostic value in predicting survival even in subanalysis according to IPSS and WHO subgroups.

CONCLUSIONS

Flow cytometric analysis in MDS may provide meaningful prognostic information. Blast percentage expressed as CD117(+) or CD34(+) cells and the quantitative assessment of myeloid maturation showed prognostic value for survival.

Flow cytometry immunophenotyping for the evaluation of bone marrow dysplasia

The pathological hallmark of myelodysplastic syndromes (MDS) is marrow dysplasia, which represents the basis of the WHO classification of these disorders. This classification provides clinicians with a useful tool for defining the different subtypes of MDS and determining individual prognosis. The WHO proposal has raised some concern regarding minimal diagnostic criteria particularly in patients with normal karyotype without robust morphological markers of dysplasia (such as ring sideroblasts or excess of blasts). Therefore, there is clearly a need to refine the accuracy to detect marrow dysplasia. Flow cytometry (FCM) immunophenotyping has been proposed as a tool to improve the evaluation of marrow dysplasia. Rationale for the application of FCM in the diagnostic work up of MDS is that immunophenotyping is an accurate method for quantitative and qualitative evaluation of hematopoietic cells and that MDS have been found to have abnormal expression of several cellular antigens. To become clinically applicable, FCM analysis should be based on parameters with sufficient specificity and sensitivity, data should be reproducible between different operators and the results should be easily understood by clinicians. In this report, we reviewed the most relevant progresses in detection of marrow dysplasia by FCM in MDS as defined by WHO criteria.

Flow cytometric scoring system as a diagnostic and prognostic tool in myelodysplastic syndromes

The aim of this study is to validate the clinical utility of the flow cytometric scoring system (FCSS), quantifying phenotypic aberrancies in the myelomonocytic lineages, in the diagnosis and prognosis for conventionally treated myelodysplastic syndromes (MDS) patients. The bone marrow samples from 56 consecutive newly diagnosed MDS patients were characterized by the FCSS and compared with findings in 27 non-MDS cytopenic patients. The FCSS scores were significantly higher in patients with MDS than those in the non-MDS control. A flow score of 2 or more allowed for a specificity of 100% with 75% sensitivity in distinguishing these two groups. The FCSS scores correlated directly with validated prognostic systems including WHO classification, International Prognostic Scoring System (IPSS), WHO-adjusted prognostic scoring system (WPSS) and transfusion dependency. The median survival of conventionally treated MDS patients was directly related to FCSS group; severe: 6 months; moderate: 19 months and normal/mild: not reached. The multivariate analyses suggested the FCSS risk categories were an independent prognostic factor after adjustment for sex, age (above or below 70 years), IPSS or WPSS risk categories. These results confirm that quantifying aberrancies in the myelomonocytic lineage by FCSS is useful in MDS diagnosis and extends the prognostic utility for conventionally treated/untreated patients, especially among patients classified within the refractory cytopenia with multilineage dysplasia (RCMD) subgroup.

Review of the relevance of aberrant antigen expression by flow cytometry in myeloid neoplasms

This article reviews the use of aberrant antigen expression detected by flow cytometry in the diagnosis and clinical handling of acute myeloid leukaemia (AML) and the myelodysplastic syndromes (MDS). Such aberrancies offer a valuable tool for the proper classification of these myeloid malignancies according the World Health Organization 2008 classification. Aberrant antigen expression by flow cytometry is also important for prognostification. This review supports the view, that minimal residual disease detection methods that make use of such aberrancies should be part of the routine management of AML patients to guide therapy, but also suggests the introduction of flow cytometry in MDS for diagnosis and treatment decisions in the near future.

Clinical utility of flow cytometry in the study of erythropoiesis and nonclonal red cell disorders

Erythropoiesis involves proliferation and differentiation of small population of hematopoietic stem cells resident in the bone marrow into mature red blood cells. The determination of the cellular composition of the blood is a valuable tool in the diagnosis of diseases and monitoring of therapy. Flow cytometric analysis is increasingly being used to characterize the heterogeneous cell populations present in the blood and the hematopoietic cell differentiation and maturation pathways of the bone marrow. Here we discuss the role of flow cytometry in the study of erythropoiesis and nonclonal red blood cell disorders. First, we discuss flow cytometric analysis of reticulocytes. Next, we review salient quantitative methods that can be used for detection of fetal-maternal hemorrhage (FMH). We also discuss flow cytometric analysis of high hemoglobin F (HbF) in Sickle Cell Disease (SCD), hereditary spherocytosis (HS), red cell survival and red cell volume. We conclude by discussing cell cycle of erythroid cells.

Diagnosis of Myelodysplastic Syndromes in Cytopenic Patients

Sustained clinical cytopenia is a frequent laboratory finding in ambulatory and hospitalized patients. For pathologists and hematopathologists who examine the bone marrow (BM), a diagnosis of cytopenia secondary to an infiltrative BM process or acute leukemia can be readily established based on morphologic evaluation and flow cytometry immunophenotyping. However, it can be more challenging to establish a diagnosis of myelodysplastic syndrome (MDS). In this article, the practical approaches for establishing or excluding a diagnosis of MDS (especially low-grade MDS) in patients with clinical cytopenia are discussed along with the current diagnostic recommendations provided by the World Health Organization and the International Working Group for MDS.

Decreased CD10 Expression in the Bone Marrow Neutrophils of HIV Positive Patients

Background:

HIV-1 infection is associated with various quantitative and qualitative changes in haemopoietic cells. Clear distinction between primary myelodysplastic syndrome (MDS) and secondary dysplasia may not always be possible. Adjunctive analyses used in the diagnosis of MDS include cytogenetics and flow cytometry (FCM). Much focus has been placed on establishing FCM guidelines aiding in the diagnosis of MDS, and to distinguish this condition from secondary dysplastic changes. One of the parameters often cited is the CD10 expression on the granulocyte population, as this marker denotes granulocytic maturation.

Aims:

To determine the expression level of CD10 on granulocytes in HIV positive patients.

Methods:

In total, 117 HIV-1 positive and 29 HIV-1 negative patients were included in this study. Bone marrow aspirate samples were evaluated in terms of morphological abnormality as well as CD10 expression on the granulocytic population.

Results:

The average CD10 expression among the HIV-1 positive patients were markedly reduced, at 18.4%, and 113 patients (96.6%) of these patients had expression levels below 50%.

Discussion:

Disease conditions causing secondary dysplasia, especially HIV-1 infection, is associated with a marked reduction in CD10 expression on the granulocyte population independent from the presence of myelodysplastic features. This marker is therefore of doubtful significance as a diagnostic tool in distinguishing between primary and secondary dysplasia.