Acute myelogenous leukemia

Definition of Acute myelogenous leukemia

Acute myelogenous leukemia (AML) is the result of a sequence of somatic mutations in a  multipotential primitive hematopoietic cell or, in some cases, a more differentiated  progenitor cell.

 Acute myelogenous leukemia  is characterized by (1) accumulation of abnormal (leukemic) blast cells, principally in the  marrow, and (2) impaired production of normal blood cells. Thus, the leukemic cell infiltration  in marrow is accompanied, nearly invariably, by anemia and thrombocytopenia. The absolute neutrophil count may be low or normal, depending on the total white cell count.

Etiology and pathogenesis of Acute myelogenous leukemia

Exposure to radiation, chronic exposure to high doses of benzene, and  chronic, heavy inhalation of tobacco smoke increase the incidence of the disease. A small but  increasing proportion of cases develop after a patient with lymphoma or a non-hematologic  cancer is exposed to intensive chemotherapy, especially with alkylating agents or  topoisomerase II inhibitors. The mutant hematopoietic cell gains a growth and/or survival  advantage in relationship to the normal pool of stem cells. As the progeny of this mutant, now  leukemic, multipotential cell proliferates to form approximately 11 billion or more cells, normal  hematopoiesis is inhibited, and normal red cell, neutrophil, and platelet blood levels fall. The  resultant anemia leads to weakness, exertional limitations, and pallor; the thrombocytopenia to  spontaneous hemorrhage, usually in the skin; and the neutropenia and monocytopenia to poor  wound healing and minor infections. Severe infection usually does not occur at diagnosis but  will if the disease progresses because of lack of treatment or if chemotherapy intensifies the  decrease of blood neutrophil and monocyte levels.

Diagnosis of Acute myelogenous leukemia 

The diagnosis is made by measurement of  blood cell counts and examination of blood and marrow cells and is based on identification of  leukemic blast cells in the marrow and blood. The diagnosis of AML specifically is confirmed by  identification of myeloperoxidase activity in blast cells or by identifying characteristic cluster of  differentiation (CD) antigens on the blast cells (e.g., CD13, CD33). The leukemic stem cell is capable of imperfect differentiation and maturation. The clone may contain cells that have the  morphologic or immunophenotypic features of erythroblasts, megakaryocytes, monocytes,  eosinophils, or, rarely, basophils or mast cells, in addition to myeloblasts or promyelocytes.  When one cell line is sufficiently dominant, the leukemia may be referred to as acute erythroid,  acute megakaryocytic, acute monocytic, and so on.

 treatment of acute myelogenous leukemia 

Acute myelogenous leukemia  usually is treated with cytarabine and an anthracycline antibiotic, although other drugs may be  added or substituted in poor prognosis, refractory,or relapsed patients. The exception to this  approach is the treatment of acute promyelocytic leukemia with all transretinoic acid, arsenic  trioxide, and an anthracycline antibiotic. High dose chemotherapy and either autologous stem  cell infusion or allogeneic stem cell transplantation may be used in an effort to treat relapse or  patients at high risk to relapse after chemotherapy treatment.

Prognosis of AML 

The probability of remission of acute myelogenous leukemia   ranges from approximately 80 percent in children to less than 25 percent in octogenarians. The  probability for cure decreases from approximately 50 percent in children to virtually zero in  octogenarians.