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

Basophils (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 2-3 lobes connected by thin chromatin filament
  • Nucleoli are absent
  • More cytoplasm with only secondary granules
  • Secondary (specific) granules are Basophilic (blue-violet) and obscure the underlying nucleus
Normal % blood-PB, marrow-BM, lymphoid tissue-LN:
  • PB: Very Rare (5th most common WBC in blood, after neutrophils, lymphocytes, monocytes, and Eosinophils)
  • BM: Rare scattered
  • LN: None
May Resemble: Differential Diagnoses:

Increased in:
CML accelerated phase
AML (rare variants)
Infection (e.g. varicella)
Hypersensitivity reactions (sometimes)

Classic Immunophenotype:
  • CD45dim+
  • Low SSC (Side light scatter)
  • CD11b+
  • CD13+
  • CD16-
  • CD15-
Cartoon Image:

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  • Increased basophils may be associated with some myeloid neoplasms such as CML, or some infections or some hypersensitivity reactions

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