![]() ![]() Our second parameter is examination of CD2, CD7, and CD56 on CD34-positive blasts. CD2, CD7 and CD56 Expression on CD34+ Blasts (orange) This heterogeneity of blasts is lost in majority of MDS cases, as shown in the lower part of the slide. As can be seen in this slide, normal CD34-positive blasts show a specific pattern of CD13/HLA-DR expression with 3 readily recognizable populations. ![]() First, we examine the expression of CD13 and HLA-DR on the population of CD34-positive blasts. Our assessment of myeloid precursors is based on 3 parameters. CD13/HLA-DR Expression on CD34+ Blasts (orange) Aberrant patterns of antigen expression can be seen in MDS and in a smaller percentage of myeloproliferative and mixed myelodysplastic/myeloproliferative neoplasms. Our test is qualitative and requires interpretation of patterns of expression of antigens, primarily on myeloid blasts, but also examines maturing granulocytic population. The panel of antibodies used in 2 tubes is the same as our acute panel, and includes CD2, CD7, CD13, CD15, CD33, CD34, CD36, CD56, CD64, CD45, CD117, and HLA-DR. Here at Mayo Clinic, we have developed a flow cytometry test for myeloid dysplasia on bone marrow aspirates, that is based on experience of our laboratory and many others. Flow Cytometry In MDS: Mayo Approach: MYEFL, test code 63414 For that reason, WHO 2008 classification stated that cases with evidence of dysplasia by flow cytometry only, should be reevaluated, essentially stating that flow cytometry is only an adjunct diagnostic modality for detection of dysplasia. In addition, most studies were performed by comparing normal with dysplastic bone marrows, without including the spectrum of atypical specimens which are usually seen in the routine practice. While qualitative studies are less sensitive to instrument settings and staining procedures, they require operator training in order to recognize normal and abnormal antigen expression patterns.įor all the reasons mentioned, flow cytometry as a diagnostic modality for MDS and other chronic myeloid neoplasms has been difficult to standardize between laboratories. In contrast, qualitative studies depend on the operator recognition of specific pattern of expression on 2-dimensional dot plots. Recently, some of these quantitative studies have utilized software for automatic gating of different cell populations and multidimensional evaluation of population attributes. For these approaches, careful instrument settings and strict staining procedures are necessary. In quantitative studies, there is a set ratio of cell population counts, or ratios of quantitative expression of antigens and side scatters on different cell populations. ![]() These studies can be divided into quantitative and qualitative. ![]() Since approximately 15 to 20 years ago, many studies have shown correlation of flow cytometry findings with presence of dysplasia defined by morphologic or cytogenetic findings. Potential role of flow cytometry immunophenotyping in the diagnosis of MDS is also mentioned. WHO classification of hematologic neoplasms from 2008 defines MDS based on clinical presentation, morphologic features of cells, blast counts, and cytogenetic and molecular genetic findings. Myeloproliferative neoplasms usually have increased peripheral blood counts, with hypercellular marrow and marrow fibrosis. MDS is characterized by block in differentiation of hematopoietic precursors, leading to cytopenias and propensity to develop acute myeloid leukemia. They can be broadly divided into myelodysplastic syndrome or MDS, myeloproliferative neoplasms or MPN, and neoplasms with mixed dysplastic and proliferative features or MDS/MPN. Chronic Myeloid NeoplasmsĬhronic myeloid neoplasms are a group of disorders that affect hematopoietic stem cells and are more frequent in adults and older patients. Thanks for the introduction, I have nothing to disclose. Jevremovic thank you for presenting with us today.
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