Aplastic anemia is a disorder of marrow failure which stems from suppression or disappearance of multipotent myeloid stem cells. It is characterized by: Anemia, Neutropenia , Thrombocytopenia, and Reticulocytopenia. Splenomegaly is characteristically absent; if present, the diagnosis of aplastic anemia is almost ruled out. Bone marrow shows hypocellular marrow largely devoid of hematopoietic cells, often only fat cells, fibrous stroma, and scattered or clustered foci of lymphocytes and plasma cells. Nucleated RBCs in peripheral smear (leukoerythroblastic picture) are found in cases of marrow fibrosis.