Blood/Blood Cells and Cellular Components ›› Neutrophils ›› Abnormal

Promyelocyte*


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Microscopic Features:
  • 2-3x larger than a mature RBC
  • High nuclear to cytoplasmic ratio (but more cytoplasm than Myeloblast)
  • Round Nucleus with immature chromatin (not clumped)
  • Nucleoli are present but less prominent than Myeloblasts
  • Small amount of cytoplasm with primary (azurophilic) granules
Normal % blood-PB, marrow-BM, lymphoid tissue-LN:
  • PB: None
  • BM: 2-6%
  • LN: None
May Resemble: Differential Diagnoses:

If in blood or increased numbers in bone marrow:
Acute promyelocytic leukemia (AKA AML M3)
Myeloproliferative Neoplasms (e.g. CML)
Leukemoid reactions
Post GCSF therapy

Classic Immunophenotype:
  • CD34-
  • CD117+
  • HLA-DR-
  • CD13+
  • CD33+
  • CD15-/+
  • MPO+
Cartoon Image:



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RBC
for direct comparison

Misc:
  • Maturation step that comes after Myeloblast and precedes Myelocyte



Content Editors/Website Administrators:
Hooman H. Rashidi, MD; John C. Nguyen, MD