Primary Hematopoietic and Lymphoid Tissue ›› Bone Marrow ›› Myeloid ›› Granulocytes & Precursors ›› Neutrophilic ›› Normal
Myeloblast
›Microscopic Features:
- 3-4x larger than a mature RBC
- High nuclear to cytoplasmic ratio (very little cytoplasm)
- Round Nucleus with immature chromatin (not clumped)
- Prominent nucleoli
- Cytoplasm is scant, gray to pale blue and lacks granules
›Normal % blood-PB, marrow-BM, lymphoid tissue-LN:
- PB: None
- BM: Scattered (~1-3%)
- LN: None
›May Resemble:
›Differential Diagnoses:
If in blood or increased numbers in bone marrow:
Acute myeloid leukemia (AML)
Myelodysplastic Syndromes (e.g. RAEB-I or II)
Myeloproliferative Neoplasms (e.g. CML with increased blasts)
Leukemoid reactions
Post-GCSF therapy
Acute myeloid leukemia (AML)
Myelodysplastic Syndromes (e.g. RAEB-I or II)
Myeloproliferative Neoplasms (e.g. CML with increased blasts)
Leukemoid reactions
Post-GCSF therapy
›Classic Immunophenotype:
- CD34+
- CD117+
- HLA-DR+
- CD13+
- CD33+
- CD15-
›Cartoon Image:
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›Misc:
Approximately 1-3% myeloblasts can be seen in a normal bone marrow but no auer rods are allowed in normal myeloblasts