Leukemia is not caused by cytopenia, but by a clonal increase in leukemic cells. Leukemia is caused by an increase in primitive or naive cells in the hematopoietic system, causing a decrease in normal cells, such as acute lymphoblastic leukemia and acute granulocytic leukemia and acute monocytic leukemia caused by an increase in lymphocytes. Cytopenias are caused by the suppression of normal bone marrow hematopoiesis after the onset of leukemia, such as acute lymphoblastic leukemia due to an increase in abnormal lymphocytes and a decrease in normal blood cells, resulting in anemia and thrombocytopenia. Therefore, patients with acute leukemia present clinically with anemia, bleeding, or thrombocytopenia.