2 Myelodysplastic Syndrome Group of clonal disorders of hematopoietic stem cells characterized by cellular dysplasia and ineffective hematopoiesisResults in cytopenias and dysmyelopoiesisVariable risk of transformation to acute leukemia
3 Pathophysiology Primary MDS or Secondary MDS A clonal mutation in hematopoietic stem cellsBone marrow failure due to ineffective hematopoiesisIncreased cytokines (TNF-a) inhibit hematopoiesisIncreased apoptosisResults in futile cycling of blood cells with impaired production of mature blood cells
4 PrevalenceMainly a disorder of older patients, rarely presents before age 50Median age is 65 yearsMale predominance
5 Clinical Presentation Non specific signs and symptoms of various cytopeniasFatigue, SOB, exercise intolerance, pallor, tachycardiaMucosal bleeding, petechiae, ecchymosesInfection, feverB-symptoms are uncommonSplenomegaly and lymphadenopathy are rare
6 Diagnosis Anemia uniformly present with decreased reticulocytosis >50% present with pancytopenia50% present with associated neutropenia<5% isolated neutropenia or thrombocytopeniaCytopenia with normal or hypercellular bone marrow with single or multi-lineage dysplasia
7 MorphologyPeripheral changes include oval macrocytic red cells, hypogranular granulocytes with the pseudo-Pelger–Huët anomaly, and giant platelets.
8 MorphologyMegaloblastic red-cell precursors with multiple nuclei or asynchronous maturation of the nucleus and the cytoplasm
9 MorphologyRinged sideroblasts, erythroid precursors with iron-laden mitochondria
10 Classification Refractory Anemia (RA) DiseasePeripheral BloodBone MarrowRefractory Anemia (RA)AnemiaNo or rare blastsErythroid dysplasia only< 5% blasts< 15% ringed sideroblastsRefractory Anemia with Ringed Sideroblasts (RARS)No blasts>15% ringed sideroblasts < 5% blastsRefractory cytopenia with multilineage dysplasia (RCMD)CytopeniaNo Auer rods< 1 × 109/L monocytesDysplasia in 10% of cells in 2 or more myeloid cell lines < 5% blasts in marrow < 15% ringed sideroblasts
11 Classification Cont.DiseasePeripheral BloodBone MarrowRefractory cytopenia with multilineage dysplasia and ringed sideroblasts (RCMD-RS)CytopeniaNo or rare blastsNo Auer rods< 1 × 109/L monocytesDysplasia in 10% of cells in 2 or more myeloid cell lines < 5% blasts in marrow > 15% ringed sideroblastsRefractory anemia with excess blasts-1 (RAEB-1)Cytopenias< 5% blastsUnilineage or multilineage dysplasia5% to 9% blastsRefractory anemia with excess blasts-2 (RAEB-2)5% to 19% blastsAuer rods ± < 1 × 109/L monocytes10% to 19% blasts±Auer rods
12 Classification cont. Disease Peripheral Blood Bone Marrow Myelodysplastic syndrome, unclassified (MDS-U)CytopeniasNo or rare blastsNo Auer rodsUnilineage dysplasia in granulocytes or megakaryocytes< 5% blastsMDS associated with isolated del(5q)AnemiaPlatelets normal or increasedNormal to increased megakaryocytes with hypolobated nucleiIsolated del(5q)
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