12.3: Acute Myelogenous Leukemia (AML)
- Page ID
- 38838
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- An image from a bone marrow smear showing an abundant amount of myeloid precursors and a few myeloblasts seen in a patient with acute myeloid leukemia. 50x oil immersion. From MLS Collection, University of Alberta, https://doi.org/10.7939/R32V2CR7N
- An image from a peripheral blood smear showing myeloblasts. One myeloblast contains a faint, pink staining, auer rod. 60x oil immersion. From MLS Collection, University of Alberta, https://doi.org/10.7939/R3C24R34V
- An image from a peripheral blood smear showing a myeloblast with multiple auer rods (stained pink) seen in AML. 100x oil immersion. From MLS Collection, University of Alberta, https://doi.org/10.7939/R3DV1D397
WHO Classification (2008):
As of 2008, acute myeloid leukemias have been classified into different subcategories based on the type of genetic abnormalities, type of myeloid cell type affected, and by cell characteristics:1
- Acute myeloid leukemia with recurrent genetic abnormalities
- Acute myeloid leukemia with myelodysplastic changes
- Therapy related myeloid neoplasms
- Acute myeloid leukemia, not otherwise specified (NOS)
- Myeloid Sarcoma
- Myeloid Proliferations related to Down syndrome
- Blastic plasmacytoid dendritic cell neoplasm
Affected Age: Adults.2
Cells of myeloid lineage are affected:1
- Myeloblast
- Monocytes
- Erythrocytes
- Megakaryocytes
- Dendritic cells
AML Blasts Cell Features:3
Size: Myeloblasts are usually larger compared to lymphoblasts and have a consistent appearance.
Nucleoli: Prominent, 1-4 present
Chromatin: Loose open chromatin
Cytoplasm: Often abundant and granules may be visible
Auer Rods: may be present (stained faint pink with Wright’s stain)
Auer Rods are thought to be fused primary granules and are only found in myeloblasts. Presence of auer rods is distinctive of AML and can be used to differentiate the condition from ALL if it is present.1
Laboratory Results for AML:1,4,5
|
CBC: RBC: Decreased WBC: Variable PLT: Decreased Hb: Decreased RDW: Increased |
PBS: Myeloblasts ± Auer rods Macrocytic RBCs May see hypogranular PLT, Giant PLT Neutropenia (Can appear dysplastic) May see Basophilia, Eosinophilia, Monocytosis |
BM: ≥20% Myeloblasts ± Auer rods Hypercellular Decreased fat |
|
Immunologic Markers: Depending on the subgroup, cells may be positive for: CD11b, CD13, CD14, CD33, CD34, CD117 |
Other Tests: LD: Increased Hyperuricemia Hyperphosphatemia Hypocalcemia Hypokalemia Cytogenetics Cytochemistry |
References:
1. Swerdlow SH, Campo E, Harris NL, Jaffe ES, Pileri SA, Stein H, et al. editors. WHO Classification of Tumours of Haematopoietic and Lymphoid Tissues Volume 2. 4th ed. International Agency for Research on Cancer (IARC); 2008.
2. McKenzie SB. Introduction to hematopoietic neoplasms. In: Clinical laboratory hematology. 3rd ed. New Jersey: Pearson; 2015. p. 424-45.
3. Gatter K, Cruz F, Braziel R. Introduction to leukemia and the acute leukemias. In: Clinical hematology and fundamentals of hemostasis. 5th ed. Philadelphia: F.A. Davis Company; 2009. p. 331-370.
4. Roquiz W, Gandhi P, Kini AR. Acute leukemias. In: Rodak’s hematology clinical applications and principles. 5th ed. St. Louis, Missouri: Saunders; 2015. p. 543-60.
5. Bentley G, Leclair SJ. Acute Myeloid Leukemias. In: Clinical laboratory hematology. 3rd ed. New Jersey: Pearson; 2015. p. 500-21.