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Acute myeloid leukemia. Dr Ramadas Nayak Professor & HOD Pathology Yenepoya Medical College Mangaluru. ACUTE LEUKEMIA. Definition Acute leukemia is a malignant disease of the bone marrow stem cell and its c haracteristic features are:
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Acute myeloid leukemia Dr Ramadas Nayak Professor & HOD Pathology Yenepoya Medical College Mangaluru
ACUTE LEUKEMIA • Definition • Acute leukemia is a malignant disease of the bone marrow stem cell and its characteristic features are: • Bone marrow: Diffuse replacement with proliferating neoplastic blast cells that fail to mature. • Blast cells more than 20% (WHO criteria) of the nucleated cells in the marrow. • Peripheral blood: Abnormal numbers and forms of immature white blood cells.
ACUTE LEUKEMIA • Aleukemic/subleukemic leukemia is characterized by very few/no blasts in the peripheral blood. • Acute leukemia are mainly divided into two groups, namely acute lymphoblastic leukemia (ALL) and acute myeloblastic leukemia (AML).
Classification • Traditional classification depending on microscopic appearance of the involved cell and the course of leukemias.
FAB Classification of Acute Leukemias • French, American and British (FAB) classification (1976) was based on the (1) morphological and (2) cytochemical characteristics of blast cells. • Revised FAB classification . It includes: • 1. Morphology and cytochemistry of blast cells • 2. Immunophenotyping • 3. Cytogenetics • 4. Molecular genetics.
ACUTE MYELOGENOUS LEUKEMIA • Definition: • Neoplasm of hematopoietic progenitors characterized by proliferation resulting in accumulation of immature myeloblasts in the marrow.
Laboratory Findings • Peripheral Blood • Total WBC Count: Markedly raised, ranging from 20 × 109/L to 100 × 109 /L. • Hemoglobin: Decreased and ranges from 5 to 9 g/dL.
Peripheral smear • RBCs: Normocytic normochromic type of anemia.
Peripheral smear • WBCs: • Total WBC count markedly increased. • Differential count: • More than 20% myeloid blasts. May show more than one type of blast or blasts with hybrid features.
Peripheral smear • WBCs: • Morphology of myeloblasts: • 3 to 5 times larger than the diameter of a small lymphocyte. • High N:C ratio. • Fine nuclear chromatin with 2–4 variably prominent nucleoli. • More cytoplasm than lymphoblasts—azurophilic, peroxidase-positive granules. • Presence of Auer rods is definitive evidence of myeloid differentiation. • Auer rods are azurophilic needle-like peroxidase-positive structures in the cytosol of myeloblasts (M2 and M3 subtype).
Cytochemistry of Myeloblasts • Stain positively with myeloperoxidase (MPO) and Sudan black B. • Monoblastsstain with nonspecific esterases.
Peripheral smear • Platelets: Moderate to severe thrombocytopenia and causes bleeding from skin and mucosa.
BONE MARROW • Cellularity: Markedly hypercellular. • Erythropoiesis: Markedly suppressed. • Myelopoiesis: Suppression of myeloid maturation and myeloblasts constitute more than 20% of marrow cells. • Megakaryopoiesis: Gradually decreased.