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

Eosinophil (Increased)*

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Microscopic Features:
  • 2-3x larger than a mature RBC
  • Low nuclear to cytoplasmic ratio (more cytoplasm than nucleus)
  • Nucleus is mature and usually with 2 lobes connected by thin chromatin filament
  • Nucleoli are absent
  • More cytoplasm with only secondary granules
  • Secondary (specific) granules are eosinophilic (red-orange)
Normal % blood-PB, marrow-BM, lymphoid tissue-LN:
  • PB: Scattered (4th most common WBC in blood, after neutrophils, lymphocytes and monocytes)
  • BM: Rare scattered
  • LN: Rare to None
May Resemble: Differential Diagnoses:

Increased in:
Allergy-related (e.g. Asthma)
Drug reactions
Invasive parasitic infections
Myeloproliferative neoplasms
Hodgkin's and non-Hodgkin's lymphomas
Autoimmune disorders (some)

Classic Immunophenotype:
  • CD45dim+
  • High SSC (Side light scatter)
  • CD13dim+
  • CD16-
  • CD15dim+
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  • Increased amounts are commonly associated with: Drugs Allergy Infection (specially invasive multicellular parasites) Neoplasm (e.g. Myeloid neoplasms such as some AMLs or MPNs) Idiopathic

Content Editors/Website Administrators:
Hooman H. Rashidi, MD; John C. Nguyen, MD