73 Acute Myelogenous Leukemia (AML)

Michelle To and Valentin Villatoro

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

  1. Acute myeloid leukemia with recurrent genetic abnormalities

  2. Acute myeloid leukemia with myelodysplastic changes

  3. Therapy related myeloid neoplasms

  4. Acute myeloid leukemia, not otherwise specified (NOS)

  5. Myeloid Sarcoma

  6. Myeloid Proliferations related to Down syndrome

  7. 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.

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Acute Myelogenous Leukemia (AML) by Michelle To and Valentin Villatoro is licensed under a Creative Commons Attribution-NonCommercial 4.0 International License, except where otherwise noted.

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