Primary Hematopoietic and Lymphoid Tissue ›› Bone Marrow ›› Myeloid ›› Erythroid (RBCs & Precursors) ›› Normal
Basophilic Normoblast
›Microscopic Features:
- 2-3x larger than a mature RBC
- High nuclear to cytoplasmic ratio
- Round Nucleus with immature chromatin (not clumped)
- Nucleoli are NOT prominent
- Cytoplasm is deep blue in color and with a perinuclear clearing
›Normal % blood-PB, marrow-BM, lymphoid tissue-LN:
- PB: None
- BM: Scattered
- LN: None
›May Resemble:
- Pronormoblast
- Polychromatophilic normoblasts
- Orthochromic normoblast
- Plasma cell precursor (Plasmablast)
- Immature B-cell (hematogone)
›Differential Diagnoses:
Increased in:
Polycythemia Vera
Post-erythropoietin therapy
Reactive Erythroid Hyperplasia
Polycythemia Vera
Post-erythropoietin therapy
Reactive Erythroid Hyperplasia
›Classic Immunophenotype:
- CD45 dim to -
- CD34-
- CD117+
- CD235a (Glycophorin A) very dim+
- CD71+
- Ecadherin +
›Cartoon Image:
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›Misc:
In normal marrow they comprise 2-3% of the total nucleated cells which is approximately 5-8% of the nucleated red blood cells precursors.Note: As Erythroid precursors mature, the color of their cytoplasm changes from blue to gray to red-orange (this is due to the increase in the number of hemoglobin molecules within the red cells as they mature). Additionally, the nucleus of the red blood cell will become more dense as it matures, eventually excreting from the cell forming the mature RBC.