1. The myelodysplastic syndromes (MDS) Aquired Clonal disease of BM. comprise a heterogeneous group of malignant stem cell disorders characterized by : 1 -d ysplastic 2 - I neffective blood cell production. …………………. (ie, apoptotic death). 3 - V ariable risk of transformation to ………………………….. acute leukemia ( AML ). These disorders may occur de novo or arise years after exposure to potentially mutagenic chemotherapy and Iradiation.

2. MDS Subtypes -Refractory anemia (RA) -RA with Ring Sideroblasts ( RARS) -RA with excess blasts (RAEB) -RAEB in Transformation (REABt) -Chronic Myelomonocytic leukemia

3. Risk Factors of MDS -Down’s syndrome -Previous Chemotherapy -Chemical Exposure ( eg Benzene ) -Iradiation

4. CLINICAL PRESENTATION of MDS : peripheral cytopenias (ie, anemia, neutropenia, and thrombocytopenia ) Many patients are asymptomatic, with a diagnosis established upon routine laboratory screening. fatigue, weakness, exercise intolerance angina, dizziness Less commonly, infection, easy bruising or bleeding.

5. Clinical features of MDS -Asymtomatic with Macrocytic anemia -Symptomatic anemia -Infections. (Neutropenia) -Hemorrhagic manifestation -General symptom. (weight loss, sweats…)

6. FAB Classification of MDS MDS FAB Subtype Blood Marrow blasts % RA Mono<1% Blast 1% <5% RARS Mono<1% Blast<1% <5% RAEB Blast<5% 5-20% RAEBt Blast Variable 20-30% Cmml Mono>5% Blast,5% <5%