USMLE

Hairy Cell Leukemia (HCL)

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Leukemias and Lymphomas
  1. Acute Myelogenous Leukemia (AML)
  2. Acute Promyelocytic Leukemia (APL)
  3. Acute Lymphocytic Leukemia (ALL)
  4. Chronic Myelogenous Leukemia (CML)
  5. Chronic Lymphocytic Leukemia (CLL)
  6. Hairy Cell Leukemia (HCL)
  7. Hodgkin Lymphoma
  8. Burkitt Lymphoma
  9. Diffuse Large B Cell Lymphoma (DLBCL)
  10. Follicular Lymphoma
  11. Mantle Cell Lymphoma
  12. Marginal Zone Lymphoma
  13. Primary CNS Lymphoma (PCNSL)
  14. Acute T-Cell Leukemia/Lymphoma (ATLL)
  15. Mycosis Fungoides / Sezary Syndrome

Summary

Hairy cell leukemia is a rare, slow-growing cancer of B-cells, characterized by hair-like cytoplasmic projections seen on peripheral blood smear. Hairy cell leukemia most frequently occurs in older men. It is commonly associated with an activating BRAF mutation, and the enzyme TRAP is upregulated in the malignant or hairy B-cells. Clinically, hairy cell leukemia commonly presents with typical leukemic symptoms, including pancytopenia due to bone-marrow invasion of malignant B-cells. Repeated bone marrow damage can cause bone marrow fibrosis, which manifests clinically as dry bone marrow taps. Splenic infiltration of malignant B-cells can also result in splenomegaly.  The purine analog cladribine is the treatment of choice.