Leukemia - Acute
AML not otherwise categorized
Acute monoblastic and acute monocytic leukemia (AML- M5)



Topic Completed: 1 February 2013

Revised: 22 January 2019, last major update February 2013

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PubMed Search: Acute monoblastic and acute monocytic leukemia AML M5

Related Topics: Acute monoblastic leukemia (M5a), Acute monocytic leukemia (M5b)


Daniela Mihova, M.D.
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Cite this page: Mihova D. Acute monoblastic and acute monocytic leukemia (AML- M5). PathologyOutlines.com website. http://www.pathologyoutlines.com/topic/leukemiaacutemonocyticleukemia.html. Accessed June 25th, 2019.
Definition / general
Diagnosis
  • 80% or more nonerythroid bone marrow cells are monocyte lineage (monoblasts, promonocytes and monocytes)
  • A minor neutrophil component < 20%
Microscopic (histologic) images

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Erythrophagocytosis in AML
M4 / M5 (see cell in upper right)

Enzyme cytochemistry
  • Monoblast granules and monocytes are strongly positive for nonspecific esterase and lysozyme, but negative for myeloperoxidase
  • More mature monocyte lineage cells may be weakly myeloperoxidase positive
  • Note: if NSE negative, confirm monocyte lineage with immunostains
Positive stains
Molecular / cytogenetics description
  • 11q23 translocations in 19%, trisomy 8 in 17%
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