Blood/Blood Cells and Cellular Components ›› Lymphocytes ›› Abnormal

Hairy Cell Leukemia*

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Microscopic Features:
  • Peripheral blood smear shows lymphocytes with hair-like cytoplasmic projections
  • Abnormal lymphocytes with hair-like projections are intermediate in size
  • Lacks a nucleolus
  • The neoplastic cells typically involve the Red Pulp area of the Spleen (as opposed to splenic Marginal zone lymphoma which involves the White pulp)
Normal % blood-PB, marrow-BM, lymphoid tissue-LN:
  • PB: None
  • BM: None
  • LN: None
May Resemble: Differential Diagnoses:

Splenic Marginal Zone Lymphoma
Reactive Lymphocytosis

Classic Immunophenotype:
  • CD19+
  • CD20+
  • CD5-
  • CD10-
  • CD103+
  • CD11c+
  • CD25+
  • Annexin1+
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  • Many cases present with splenomegaly, cytopenia or pancytopenia (many with monocytopenia), and a dry bone marrow aspirate.

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