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Hairy cell leukemia: current concepts
Timothy Cannon1, Dalia Mobarek, Julia Wegge
1Division of Hematology/Oncology, George Washington University Medical Center, Washington, DC, USA.
Insights
Hairy cell leukemia (HCL) is a rare B-cell neoplasm affecting males more than females. Advances in purine analogue treatments have significantly improved patient prognosis and remission rates.
Area of Science:
- Hematology
- Oncology
- Immunology
Background:
- Hairy cell leukemia (HCL) is a chronic lymphoproliferative disorder and a mature B-cell neoplasm.
- It accounts for 2-3% of leukemia cases, with approximately 600 new U.S. diagnoses annually.
- HCL predominantly affects males, with a median age of onset at 52 years, and is more common in Caucasians.
Purpose of the Study:
- To provide a comprehensive overview of Hairy Cell Leukemia.
- To discuss the characteristic features, epidemiology, and clinical manifestations of HCL.
- To highlight the impact of recent treatment advancements on patient outcomes.
Main Methods:
- Review of WHO classification for HCL diagnosis.
- Analysis of epidemiological data regarding HCL incidence and demographics.
- Summary of clinical presentation and pathological features of HCL.
- Evaluation of treatment outcomes with purine analogues.
Main Results:
- Hairy cells are distinct clonal B cells with characteristic morphology and surface markers (CD103, CD22, CD11c).
- Common clinical presentations include splenomegaly and pancytopenia, with potential complications like infections and vasculitis.
- Purine analogue therapies (Cladribine, Pentostatin) have led to significant improvements in response rates and durable remissions.
Conclusions:
- Hairy cell leukemia, while historically fatal, now has a significantly improved prognosis due to effective treatments.
- Modern therapies offer high response rates and long-lasting remissions for HCL patients.
- Continued research into HCL pathogenesis and treatment remains crucial.
Abstract:
Hairy cell Leukemia (HCL) is a chronic lymphoproliferative disorder that was characterized in the late 1950s. HCL is defined, according to the WHO classification, as a mature (peripheral) B-cell neoplasm (1). HCL accounts for between 2-3% of all leukemia cases, with about 600 new cases diagnosed in the U.S. each year (1). HCL occurs more commonly in males, with an overall male to female ratio of approximately 4:1. The median age of onset is 52 years. This disease is seen more commonly in Caucasians and appears to be especially frequent in Ashkenazi Jewish males, with rare occurrence in persons of Asian and African descents (1). Hairy cells are distinct, clonal B cells arrested at a late stage of maturation. They are small B lymphoid cells that possess oval nuclei and abundant cytoplasm with characteristic micro-filamentous ("hairy") projections. They strongly express CD103, CD22, and CD11c (2). These cells typically infiltrate the bone marrow, the spleen, and to a lesser extent the liver, lymph nodes, and skin. Many patients present with splenomegaly and pancytopenia. Other clinical manifestations include recurrent opportunistic infections and vasculitis. Historically, HCL was considered uniformly fatal (2). However, recent treatment advances, using purine analogues such as Cladribine and Pentostatin, led to a significant improvement in prognosis with achievement of high response rates and durable remissions (2).
