Primary Hematopoietic and Lymphoid Tissue ›› Bone Marrow ›› Myeloid ›› Granulocytes & Precursors ›› Neutrophilic ›› Normal
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
- Cytoplasm with primary (azurophilic) granules
›Normal % blood-PB, marrow-BM, lymphoid tissue-LN:
- PB: None
- BM: Scattered (~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
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-/+
›Cartoon Image:
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for direct comparison
for direct comparison
›Misc:
Scattered promyelocytes can be seen in a normal bone marrow but no auer rods are allowed in normal promyelocytes