What is the role of blood counts and blood smears in the workup of pediatric acute myelocytic leukemia (AML)?

Updated: Sep 12, 2017
  • Author: Mark E Weinblatt, MD; Chief Editor: Jennifer Reikes Willert, MD  more...
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The hallmark of acute myeloid leukemia is a reduction or absence of normal hematopoietic elements. Anemia is usually normocytic, with a reticulocyte count lower than expected for the level of the hemoglobin. The decrease in hemoglobin levels can range from minimal to profound.

Platelet counts are usually low and generally commensurate with the degree of bleeding. Patients with spontaneous petechiae usually have platelet counts of less than 20 X 109/L (< 20,000/μL).

WBC counts may be decreased or elevated. Hyperleukocytosis with WBC counts of more than 100 X 109/L (>100,000/μL) are occasionally observed; with high numbers, the blood specimen appears white. The WBC differential is usually the key to evaluating suspected leukemia; primitive granulocyte or monocyte precursors are observed on peripheral smears. Numbers of mature neutrophils are usually diminished.

Upon careful examination of the blood smears, Auer rods (thin, needle-shaped, eosinophilic cytoplasmic inclusions) are revealed in specimens of circulating blood obtained from many patients acute myelocytic leukemia. They are particularly prominent in children with APL.

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