Leukemia - Acute
AML not otherwise categorized
Acute myeloid leukemia with maturation (FAB AML M2)

Author: Daniela Mihova, M.D. (see Authors page)

Revised: 3 April 2018, last major update February 2013

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PubMed Search: Acute myeloid leukemia [title] with maturation (FAB AML M2)

Cite this page: Mihova, D. Acute myeloid leukemia with maturation (FAB AML M2). PathologyOutlines.com website. http://www.pathologyoutlines.com/topic/leukemiaM2.html. Accessed December 16th, 2018.
Definition / general
  • 10% of AML cases; 5% of childhood leukemias
  • Any age, 20% are < 25 years and 40% are 60 years+
  • Anemia, thrombocytopenia, neutropenia; variable number of blasts in peripheral blood
  • Variable prognosis
  • Criteria for diagnosis: 20%+ nonerythroid cells in peripheral blood or bone marrow are myeloblasts; monocytic precursors are < 20% in bone marrow and granulocytes are 10%+ of cells
  • Enzyme cytochemistry: most blasts are positive for myeloperoxidase or Sudan Black B, and chloroacetate esterase
Case reports
Microscopic (histologic) description
  • Usually hypercellular marrow
  • Full range of myeloid maturation through maturing neutrophils, often with abnormal segmentation and 10%+ bone marrow cells with variable degree of dysplasia
  • Auer rods in 70% of blasts; myeloblasts with or without azurophilic granules
  • Erythroid and megakaryocyte precursors may have dysplastic changes
  • Often increased eosinophilic precursors without cytological and cytochemical abnormalities of inv(16)(p13.1q22)
  • Basophils may be increased, rarely mast cell hyperplasia (Indian J Pathol Microbiol 2007;50:655)
Microscopic (histologic) images

Images hosted on PathOut server:

Bone marrow smears (Wright-Giemsa):
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Type III myeloblasts (> 20 azurophilic granules)

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Several myeloblasts, promyelocytes, myelocytes
and neutrophils and also several erythroblasts


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Several myeloblasts and maturing forms,
also neutrophils with agranular cytoplasm

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Large myeloblasts have pseudopods, usually abundant
cytoplasm and some with prominent Auer rods


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Several blasts have prominent nucleoli and
Auer rods, also a promyelocyte and myelocyte



Stains:
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Myeloperoxidase+ blasts,
neutrophils are intensely positive

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Myeloperoxidase+ blasts and immature
neutrophils, erythroid cells are negative



Bone marrow biopsy:
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Markedly hypercellular marrow has predominantly blasts,
also scattered erythroid precursors and eosinophils



Diagnosed as AML with maturation because no t(15;17) and no DIC, but FISH not done, so may actually be acute promyelocytic leukemia:
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With specific granules resembling
Chediak-Higashi anomaly

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With numerous promonocytes

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Abundant coarse azurophilic granules

Positive stains
Negative stains
Molecular / cytogenetics description
Electron microscopy images

Images hosted on PathOut server:
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Numerous primary granules and fusion of Auer rods