Blood/Blood Cells and Cellular Components ›› Neutrophils ›› Abnormal
Promyelocyte
›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:
- Myeloblast
- Myelocyte
- Metamyelocyte
- Reactive lymphocyte
- Neurophil with toxic granules
- Segmented Neutrophil
- Large Granular Lymphocyte
›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
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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for direct comparison
for direct comparison
›Misc:
Maturation step that comes after Myeloblast and precedes Myelocyte