Life Science Journal 2012;9(3) http://www.lifesciencesite.com http://www.lifesciencesite.com editor@ Life Science Journal.org 647 Diagnostic Value of Flow Cytometry in Cases with Myelodysplasia Islam M. Hussien 1 , Samia F. El-Belbessy 1 , Shereen M. El-Maghraby 1 , Amani F. Sorour 2 and Nahla Farahat 2 1 Hematology Department, Medical Research Institute, Alexandria University 2 Clinical Pathology Department, Faculty of Medicine, Alexandria University shereenmaghraby36@yahoo.com Abstract: Background: Myelodysplastic syndrome (MDS) is a term used to encompass a spectrum of clonal (neoplastic) myeloid disorders The combination of obvious marrow dysplasia and clonal karyotypic abnormalities is considered diagnostic for MDS, with each technology confirming the other. However, not all patients with MDS will have this combination of findings. In this study, we evaluated the utility of flow cytometric immunophenotyping in the diagnosis of MDS. Material and Methods: We studied 20 patients with MDS , two of them were chronic myelomonocytic leukemia (CMML) (as diagnosed by morphologic evaluation of the initial bone marrow specimen) and compared results with those obtained in healthy controls subjects. All patients and controls were subjected to full history taking , Clinical examination, complete blood count, Bone marrow aspirate ,iron stain and immunophenotyping using a panel of antibodies CD13, 33, 34, 38, 16, 14,45 ,56 and CD11b to analyze dyspoiesis by quantifying the expression of each monoclonal antibodies (MoAb) on blasts ,granulocytes and monocytes with respect to controls. Bone marrow biopsy was done in some cases. Results: The results are classified according to the gate into blast, granulocytes and monocytic gates. On blast gate, we found statistically significant increase in expression and percentage of CD34 + cells , also decrease in CD 38 expression on CD34 + cells in cases of MDS in comparison to control group. Granulocytic gating revealed statistically significant increase of CD13 expression and decrease in CD56 expression in cases in comparison to control group, while the differences in expression of CD45, CD14, CD33 and CD11B were statistically insignificant. Monocytic gating revealed statistically significant decrease of CD38 expression in cases of RA and increase of CD14 & CD11b expressions in cases in comparison to control group, while the differences in expression of CD45, CD13, CD33 and CD56 were statistically insignificant. Conclusion: We emphasis on the role of flow cytomerty in MDS for accurate blast count and identification of abnormal myeloblasts on the basis of antigenic profiles, even in the marrow with less than 5% of myeloblasts. Also recognition of immunophenotypic dysplastic changes in mature myeloid cells and monocytes. No one single simple immunophenotypic parameter has been proved to be diagnostic of MDS. [Islam M. Hussien, Samia F. El-Belbessy, Shereen M. El-Maghraby, Amani F. Sorour and Nahla Farahat. Diagnostic Value of Flow Cytometry in Cases with Myelodysplasia. Life Sci J 2012;9(3):647-656] (ISSN:1097-8135). http://www.lifesciencesite.com . 91 Keywords: MDS, Flow cytometry 1. Introduction The myelodysplastic syndromes (MDSs) are characterized by bilineage or trilineage dysplasia. Although diagnostic criteria are well established for MDS, a significant number of patients have blood and bone marrow findings that make diagnosis and classification difficult. The diagnosis of MDS is based on a combination of clinical history, the morphological features of the peripheral blood (PB) and BM (e.g., percentages of blasts and dysplasia of cells), cytogenetic data, and ruling out other diseases.(1) However, clonal cytogenetic abnormalities are typically found in less than 50% of these disorders, while morphologic evaluation is intrinsically subjective. Because reproducible patterns of antigen expression are identified in both normal myeloid maturation and benign/reactive settings such as marrow regeneration following injury, significant deviations from these benign maturational patterns can provide objective evidence supporting the presence of MDS or chronic myelomonocytic leukemia .(2) A diagnostic challenge exists in low-grade MDS that lack conventional, specific diagnostic markers, ringed sideroblasts and karyotypic aberration. The diagnosis of this category (called low-grade MDS ) largely relies on the presence of dysplasia, and therefore experienced examiners (hematologists/hematopathologists) are required to make the diagnosis. On the other hand, the dysplastic features of myeloid cells do not in themselves establish a diagnosis. Conditions other than MDS can induce dysplastic myeloid cells (e.g., deficiencies of vitamin B 12 and folate, viral infections, ethanol or lead), and thus such conditions should be ruled out by careful history taking and physical and laboratory examinations. (3) Flow cytometric immunophenotyping is an accurate method for quantitative and qualitative evaluation of hematopoietic cells, and several groups have used flow cytometry in the study of MDS. MDS patients have been found to have abnormal expression of several surface antigens, as indicated by either the