Acute myeloid leukemia (AML)
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also known as acute myelogenous leukemia or acute nonlymphocytic leukemia (ANLL), is a cancer of the myeloid line of blood cells, characterized by rapid growth of white blood cells abnormal that they accumulate in the bone marrow and interfere with the production of normal blood cells. AML is the most common acute leukemia affecting adults, and its incidence increases with age. Although AML is a relatively rare disease, accounting for about 1.2% of cancer deaths in the United States, its incidence is expected to increase as the population ages.
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The symptoms of AML are caused by the replacement of normal bone marrow with leukemic cells, causing a decline in red blood cells, platelets and normal white cells. These symptoms include fatigue, shortness of breath, easy bruising and bleeding, and increased risk of infection. Several risk factors and chromosomal abnormalities have been identified, but the specific cause is unclear. As an acute leukemia, AML progresses rapidly and is typically fatal within weeks or months if left untreated.
AML has several subtypes; treatment and prognosis varies among subtypes. LMA is cured in 35-40% of people under 60 years of age and 5-15% over 60 years old. Older people who are not able to withstand intensive chemotherapy have a median survival of 5-10 months.
AML is treated initially with chemotherapy aimed at inducing a remission; Patients may receive additional chemotherapy or hematopoietic stem cells. Recent research on the genetics of AML has resulted in the availability of tests that can predict which drug or drugs may work best for a particular patient, and the time the patient is likely to survive. Treatment and prognosis of AML differ from those of chronic myelogenous leukemia (CML) in part because cell differentiation is not the same; AML involves a higher percentage of undifferentiated and differentiated cells, including more blasts (myeloblasts, Monoblasts and megakaryoblasts).
The first clue to the diagnosis of AML is typically an abnormal result on a complete blood count. While an excess of abnormal white blood cells (leukocytosis) is a common finding, and leukemic blasts are sometimes seen, AML can also present with decreases isolated on platelets, red blood cells, or even with a low white blood cell count (leukopenia) . While a presumptive diagnosis of AML can be done by examining peripheral blood smear when there are circulating leukemic blasts, a definitive diagnosis usually requires a bone marrow aspiration and biopsy appropriate.
Marrow or blood is examined under a light microscope and flow cytometry to diagnose the presence of leukemia, to differentiate AML from other types of leukemia (acute lymphoblastic leukemia, for example - ALL), and to classify subtype of disease. A sample of bone marrow or blood is typically also tested for chromosomal abnormalities by routine cytogenetics or fluorescent in situ hybridization. Genetic studies can also be performed to look for specific mutations in genes such as FLT3, nucleophosmin, and KIT, which may influence the outcome of the disease.
staining of blood smear and bone marrow are useful in distinguishing AML all, and subclassification of AML. The combination of myeloperoxidase or Sudan black dye and stain provide nonspecific esterase desired information in most cases. The reactions of myeloperoxidase or Sudan black are more useful to determine the identity of AML and ALL distinguish. Nonspecific esterase stain is used to identify a monocyte component in AML and to distinguish a poorly differentiated monoblastic leukemia ALL.
The diagnosis and classification of AML can be challenging, and should be done by a hematologist or qualified hematopathologist. In simple cases, the presence of certain morphological characteristics (eg Auer rods) or flow cytometry results can distinguish specific AML other leukemias; however, in the absence of such features, diagnosis may be more difficult
The two most commonly used classification schemes for AML are the oldest French-American-British system (FAB) system and the newer World Health Organization (WHO). According to WHO criteria widely used, the diagnosis of AML is established by demonstrating involvement of more than 20% of the blood and / or bone marrow by leukemic myeloblasts, except in the three best ways prognosis of AML with abnormalities recurrent genetic, inv yt in which the presence of the genetic abnormality diagnostic is independently percent explosion. The French-American-British (FAB) is a little stricter, requiring a percentage of blasts of at least 30% in the bone marrow (BM) or peripheral blood (PB) for the diagnosis of AML. AML must be carefully differentiated from "pre-leukemic" conditions such as myelodysplastic syndromes or myeloproliferative, which are treated differently.
Because acute promyelocytic leukemia (APL) has the highest curability and requires a unique form of treatment, it is important to quickly establish or exclude the diagnosis of this subtype of leukemia. Fluorescent in situ hybridization performed on blood or bone marrow is often used for this purpose as it easily identifies the chromosomal translocation [t (15; 17) (q22; q12)] that characterizes APL. There is also a need for molecularly detect the presence of protein / RARA fusion PML, which is an oncogene product that translocation.
World Health Organization
The WHO classification of acute myeloid leukemia attempts to be more clinically useful and to produce more meaningful information than the FAB criteria prognosis. Each of the WHO categories contains numerous descriptive subcategories of interest to the hematopathologist and oncologist
signs of leukemia ,chronic lymphocytic leukemia , acute lymphocytic leukemia
