Leukemia is categorized by the kind of white blood cells transformed, and by how fast the disease proceeds. Lymphocytic leukemia occurs in the white blood cells called lymphocytes in the bone marrow. Myeloid leukemia may also start in white blood cells other than lymphocytes, as well as red blood cells and platelets.
Leukemia can be either severe or chronic. Chronic leukemia grows more slowly than acute leukemia, which needs urgent treatment. Leukemia is also listed as lymphocytic or myelogenous. Lymphocytic leukemia relates to abnormal cell increase in the marrow cells that convert lymphocytes, a type of white blood cell that performs a role in the immune system. In myelogenous leukemia, irregular cell growth happens in the marrow cells that mature into red blood cells, white blood cells, and platelets.