PB1959 THE ROLE OF FLOW CYTOMETRY IN DIFFERENTIAL DIAGNOSIS OF CMML AND REACTIVE MONOCYTOSIS. THE LIPID SIGNAL PATHWAY CHARACTERISTICS IN CLONAL MONOCYTOSIS

Background: Myelodysplastic syndrome (MDS) is a heterogeneous group of diseases characterized by ineffective erythropoiesis and dysplasia. MDS and its subtype CMML is highly associated with chronic inflammatory and autoimmune diseases; however the combination of MDS with other bone marrow neoplasms is not a common entity. Only few cases of MDS combined with other blood malignancies have been described. The pathogenesis and mechanisms of two different clones evolution in MDS is an unclear multistep process involving molecular genetic instability, epigenetic factors and innate immune response deregulation. The role of plasma lipid signaling pathway have been also defined in recent years. Aims: Is to investigate the role of immunophenotyping in differential diagnosis of CMML and reactive monocytosis and clarify the possible significance of phosphoinositides in diagnosis of CMML. Methods: Blood samples of patient with CMML combined with plasma cell disorder, patient with CMML and blood samples of 2 patients with monocytosis were examined in our laboratory. Peripheral blood CBC, bone marrow smear cytological examination, pathohistology, flow cytometry and PCR were performed for the diagnostic purposes. In parallel with classic diagnostic work‐up the chromatograph method was used to investigate the cytoplasmatic mono and di‐phosphoinositides in patients with CMML. Results: CBC reveal monocytosis >1000 less than 1 month duration, PCR analysis were negative for BCR ABL in all 4 cases. Case N = 1 histology examination Results: >30% of plasma cells express CD56 and CD138, atypical cells express MPO and CD14 and epithelioid granulomas. In case N = 1 Immuntophenotype results were the following: (CD64+)‐52%, (CD16+)‐44%, (CD14‐). In case N = 2 the dysplasia, megakaryocytes and monocytes were observed by histology examination. Immunophenotype Results: (CD14+/CD16)‐31.1%, (CD14+/‐CD16+)‐49.3%, (CD14‐/CD16‐)‐4.3%. There were monocytosis and secondary changes of hematopoietic tissue in histology examination of cases N = 3 and N = 4. Immunophenotype showed: (CD14‐/16‐)‐13%, (CD64+)15%, (CD56‐)‐3%. High level of mono and di‐phosphoinositides were registered in first 2 cases in compare with cases N3 and N4. The flow cytometry revealed monocyte specific markers in all 4 cases with certain variations. Summary/Conclusion: The exact immunophenotype markers for clonal monocytosis must be defined. Lipid signaling pathway components, such as cytoplasmatic mono and di‐phosphoinositides must be investigated in the context of clonal monocytosis and diagnostic purposes.