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Acute Myeloid Leukemia

 

 

Bone Marrow

 

The diagnosis is made by bone marrow aspiration and biopsy.

The posterior iliac crest is the preferred site for most children.

 

If 20% or more of the nucleated cells are blasts, then the diagnosis of AML can be made.

 

Patients with cytopenias and bone marrow blasts <20%, but who have a karyotypic

abnormality characteristic of AML, can be diagnosed as having AML.

Bone Marrow Aspirate:

 

The bone marrow aspirate in AML (above) is

  • Hypercellular with a total cellularity of nearly 100%. Approximately 82% of the nucleated cells are blasts resembling those seen in the peripheral blood.
  • These blasts are:
    • Medium to large in size
    • Variably abundant cytoplasm
    • No Auer rods
    • Mildly irregular nuclear margins and very fine chromatin
  • Mature neutrophils show the same dysplastic nuclear morphology as was noted in the peripheral circulation.
  • Erythropoiesis is generally normoblastic.
  • Megakaryocytes are also generally unremarkable, although rare examples of hypo-lobated forms are identified.
  • The sample was stained with non-specific esterase (NSE), myeloperoxidase (MPO) and iron (results are not provided). NSE and MPO staining are both negative, though stainable iron is present within granules.

 

Bone Marrow biopsy:

Low power View

Medium power view

 

High power View

 

The bone marrow biopsy above is characteristic of AML and shows that:

  • The space is nearly completely occupied by a sheet of blasts.
  • Blasts have a limited amount of cytoplasm, generally regular nuclear contours, fine chromatin, and prominent nucleoli.
  • Residual hematopoiesis is minimal.

 

 

 

 

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