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

Eosinophilic Precursor*


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› Microscopic Features:

• 2-3x larger than a mature RBC
• Low nuclear to cytoplasmic (N/C) ratio (more cytoplasm than nucleus)
• Nucleus is mature and usually with 1 lobe
• Nucleoli may be present depending on stage of maturation
• Secondary (specific) granules are eosinophilic (red-orange) in Myelocyte to mature eosinophil stage

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

• PB: None
• BM: 1-2%
• LN: None

› May Resemble:

• Mature Eosinophil [Compare]
• Neutrophilic Myelocyte [Compare]
• Neutrophilic Metamyelocyte [Compare]
• Segmented Neutrophil [Compare]
• Pseudo-Pelger Huet Neutrophil [Compare]
• Band Neutrophil [Compare]
• Neutrophil with toxic granules [Compare]
• Promyelocyte [Compare]
• Basophil [Compare]

› Differential Diagnoses:

Increased in: Myeloproliferative neoplasms (some) Allergy-related (e.g. Asthma): In bone marrow Drug reactions: In bone marrow Invasive parasitic infections: In bone marrow AML (rare variants)

› Classic Immunophenotype:

• CD45dim+
• High SSC (Side light scatter)
• CD13dim+
• CD16-
• CD15dim+
• (May have some immunophenotypic variability compared to mature eosinophils based on the stage of maturation of the precursor)

› Cartoon Image:


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› Misc:

• Hypolobation is due to its immaturity.