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Hairy Cell Leukemia

Rare chronic B-cell lymphoproliferative disorder marked by pancytopenia, splenomegaly, and characteristic hairy lymphocytes.

Written by: Saygı Hospital Health Guide Editorial Board
Last updated:

This content has been compiled by the Saygı Hospital Health Guide Editorial Board and is periodically reviewed by a specialist physician.

References (5)

This content is for informational purposes only and does not constitute medical advice. You can book an appointment at our Hematoloji department. Book Appointment →

What is Hairy Cell Leukemia?

Hairy cell leukemia (HCL) is a rare chronic B-cell lymphoproliferative disorder accounting for about 2% of adult leukemias, characterized by abnormal mature B lymphocytes with cytoplasmic projections (hairy cells) infiltrating bone marrow, peripheral blood, and splenic red pulp. Median age at diagnosis is approximately 55 years with a strong male predominance.

Almost all classic HCL cases harbor the BRAF V600E mutation, which serves as both a diagnostic marker and a therapeutic target. A variant form (HCL-v) lacks BRAF mutation, often carries MAP2K1 mutation, and shows poorer response to standard therapy. Splenomegaly without lymphadenopathy is typical, and recurrent infections from monocytopenia and neutropenia are characteristic.

Diagnosis combines morphology (cytoplasmic hairy projections), flow cytometry (CD11c, CD25, CD103, CD123 positivity), bone marrow biopsy showing reticulin fibrosis, and molecular testing for BRAF V600E. First-line treatment is purine nucleoside analogs (cladribine, pentostatin) producing complete remission rates over 80%. Relapsed/refractory disease responds to BRAF inhibitors (vemurafenib, dabrafenib) with or without MEK inhibitors (trametinib), rituximab combinations, and the immunotoxin moxetumomab pasudotox.

Symptoms

Fatigue, weakness from anemia
Splenomegaly with abdominal fullness
Recurrent bacterial or atypical infections
Bruising, petechiae from thrombocytopenia
Weight loss, night sweats
Pallor
Left upper quadrant discomfort
Pancytopenia on routine blood counts
Monocytopenia (characteristic)
Mild hepatomegaly
Bone pain (rare)
Vasculitis-like skin lesions
Opportunistic mycobacterial infections
Splenic rupture (rare)
Asymptomatic incidental finding

Risk Factors

Male sex (4:1 male:female ratio)
Age over 50
Caucasian ethnicity
BRAF V600E somatic mutation
Possible occupational exposures (farming, pesticides, organic solvents)
Ionizing radiation exposure
Prior chemotherapy (rare)
First-degree family history (rare)
Smoking (weak association)
Epstein-Barr virus (debated)
Immunosuppression (rare)
Vietnam-era Agent Orange exposure (debated)
Wood-dust exposure (debated)
No clear lifestyle predictors
Idiopathic in most cases

When to See a Doctor?

If you experience any of the following symptoms, seek medical attention promptly:

  • Persistent fatigue with pancytopenia on blood test
  • Unexplained splenomegaly
  • Recurrent or atypical infections
  • Easy bruising or bleeding
  • Unintentional weight loss with night sweats
  • Abnormal lymphocytes on peripheral smear
  • Monocytopenia with cytopenias
  • Left upper quadrant pain or fullness
  • Persistent low blood counts despite supportive care
  • Family history of B-cell malignancy with cytopenias

Treatment Methods

01
Confirm diagnosis with peripheral blood flow cytometry (CD11c, CD25, CD103, CD123)
02
Bone marrow aspiration and trephine biopsy with reticulin stain
03
BRAF V600E mutation testing (PCR or immunohistochemistry with VE1 antibody)
04
Annexin A1 immunostain to differentiate from HCL variant
05
Distinguish classic HCL from HCL-variant and splenic marginal zone lymphoma
06
Watchful waiting in asymptomatic minimally cytopenic patients
07
First-line cladribine 0.1 mg/kg/day continuous infusion for 7 days or 5 days subcutaneous
08
Alternative pentostatin 4 mg/m2 IV every 2 weeks until best response
09
Combination cladribine plus rituximab improves complete molecular remission
10
BRAF inhibitor vemurafenib or dabrafenib plus MEK inhibitor trametinib for relapsed disease
11
Moxetumomab pasudotox (anti-CD22 immunotoxin) for multiply relapsed disease
12
Ibrutinib in HCL variant
13
Splenectomy historically used, now rarely indicated except massive splenomegaly with cladribine intolerance
14
Antimicrobial prophylaxis for opportunistic infections during purine analog therapy
15
Pneumocystis jirovecii prophylaxis with trimethoprim-sulfamethoxazole
16
Antiviral prophylaxis with acyclovir or valacyclovir
17
Growth factor support (G-CSF) for severe neutropenia
18
Long-term hematology follow-up for relapse and second malignancies
19
Patient education on infection avoidance and prompt reporting of fever

Which Department to Visit?

You can visit our Hematoloji department for these complaints. Our specialist physicians will create the most suitable treatment plan for you.

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Health Disclaimer: The information on this page is prepared for general informational purposes only. It does not replace medical diagnosis and treatment. Please consult your physician for your complaints. Saygı Hospital does not accept responsibility for actions taken based on the information on this page.