Primary Hematopoietic and Lymphoid Tissue ›› Bone Marrow ›› Normal

Polychromatophilic Normoblast*


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› Microscopic Features:

• 2x larger than a mature RBC
• Intermediate nuclear to cytoplasmic ratio
• Round Nucleus with mature chromatin (clumped)
• Nucleoli are Absent
• Cytoplasm is grayish in color

› Normal % blood-PB, marrow-BM, lymphoid tissue-LN:

• PB: None
• BM: Many
• LN: None

› May Resemble:

• Orthochromic normoblast [Compare]
• Plasma cell (mature) [Compare]
• Basophilic normoblast [Compare]
• Lymphocyte (mature) [Compare]

› Differential Diagnoses:

Increased in: Reactive Erythroid Hyperplasia Post-erythropoietin therapy Polycythemia Vera

› Classic Immunophenotype:

• CD45-
• CD117-/+
• CD235a (Glycophorin A) dim+
• CD71+

› Cartoon Image:


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› Misc:

• Normally confined in bone marrow where they comprise many of the nucleated red blood cell 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 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.