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Myeloid leukemia is classified as acute myelogenous leukemia (AML) or chronic myelogenous leukemia (CML). The disease is a type of cancer that usually affects the development of white blood cells, though some forms may disrupt red blood cell development. Headaches, joint pain, and an increased susceptibility to infection are symptoms of both forms of the disease. Patients may also bleed or bruise easily and suffer excessive fatigue from anemia.
AML or CML may develop following chemotherapy or radiation for other cancers. It may also occur following a viral infection or exposure to benzene chemicals. Myelogenous leukemia can also be further classified according to the type of blood cell affected.
CML is characterized by abnormal white blood cells at varying stages of development. It is usually seen in adults over the age of 55. Men are more likely than women to be diagnosed with CML.
Undifferentiated AML, or M0, may produce mature white blood cells, but the cells never differentiate into a specific type. In myeloblastic leukemia, or M1, cells may or may not mature, but do exhibit some differentiation into the various types of granulocytic cells. The myeloblastic leukemia, referred to as M2, usually produces granulocytes in different stages of development and is sometimes classified as a genetic or chromosomal disorder.
Promyelocytic leukemia, or M3, typically is characterized by abnormal white cells that exhibit granulation and that range in maturity from myeloblasts to myelocytes. The nuclei of these cells also vary in shape and size. Disseminated intravascular coagulation (DICM3), a bleeding and clotting disorder, may occur in connection with this form of the disease. This affliction generally begins with hypercoagulation, forming blood clots throughout the body. The excessive secretion of coagulating proteins quickly causes depletion, resulting in uncontrolled bleeding.
Myelomonocytic leukemia, also known as M4, produces granulocytes as well as monocytes, both at varied stages of development. These abnormal cells usually exceed the number of all the nucleated blood cells. Unlike other forms of myeloid leukemia, M4 may also affect eosinophil development. Monocytic leukemia, or M5, results in unusually large, but immature monoblasts. Patients with this form of myeloid leukemia often experience bleeding, swollen and painful gums, or rash-like eruptions on the skin.
People diagnosed with erythroleukemia, or M6, generally exhibit abnormalities in those cells that would mature into red blood cells. Megakaryoblastic leukemia, or M7, typically exhibits enlarged, immature lymphocytes. This type of myeloid leukemia also frequently produces deposits of fibrous tissue throughout the bone marrow.