What is the appropriate management for hypereosinophilia?

Management of Hypereosinophilia

The appropriate management of hypereosinophilia requires first excluding secondary causes, then treating the underlying condition if identified, with corticosteroids (prednisolone 30-60 mg/day) as first-line therapy for idiopathic hypereosinophilic syndrome. 1

Diagnostic Approach

Definition and Initial Evaluation

• Hypereosinophilia is defined as peripheral blood eosinophil count >1.5 × 10^9/L 1, 2
• Comprehensive evaluation should include:
  • Complete blood count with differential
  • Peripheral blood smear
  • Comprehensive metabolic panel with liver function tests
  • Urinalysis with protein-to-creatinine ratio
  • C-reactive protein
  • Serum tryptase
  • Vitamin B12 levels 1

Critical History Elements

• Travel to tropical/subtropical areas
• Exposure to freshwater
• Consumption of raw foods
• Walking barefoot
• Current and recent medications
• Allergy history 1

Advanced Testing

• Bone marrow examination
• Cytogenetics
• Fluorescence in situ hybridization
• Molecular testing for PDGFRA, PDGFRB, FGFR1, or PCM1-JAK2 rearrangements
• Flow immunophenotyping
• T-cell clonality assessment 2

Treatment Algorithm

1. Secondary Causes

• Parasitic Infections:

  • Strongyloidiasis: ivermectin 200 μg/kg/day for 1-2 days
  • Toxocariasis: albendazole 400mg twice daily for 5 days
  • Schistosomiasis: praziquantel 40 mg/kg twice daily for 5 days
  • Hookworm: albendazole 400 mg daily for 3 days
  • Whipworm: mebendazole 100 mg twice daily + ivermectin 200 μg/kg once daily for 3 days
  • Threadworm/pinworm: albendazole 400 mg twice daily for 21 days 1

• Allergic Disorders:

  • For eosinophilic esophagitis: topical steroids (fluticasone 440-880 mg twice daily for adults) 1

2. Myeloid/Lymphoid Neoplasms with Eosinophilia

• With PDGFRA or PDGFRB rearrangements:

  • Imatinib (tyrosine kinase inhibitor) - first-line therapy due to excellent response 1, 2

• With FGFR1 rearrangements:

  • Pemigatinib for relapsed/refractory cases 2

3. Idiopathic Hypereosinophilic Syndrome (HES)

• First-line therapy:

  • Prednisolone 30-60 mg/day 1

• Steroid-refractory cases:

  • Hydroxyurea
  • Interferon-alpha 1, 2

• Biologic agents:

  • Mepolizumab (anti-IL-5) - FDA approved for idiopathic HES 2
  • Benralizumab (anti-IL-5 receptor)
  • Dupilumab and cendakimab (investigational) 1

4. Lymphocyte-Variant Hypereosinophilia

• First-line therapy:
  • Corticosteroids 2

5. Aggressive Forms (HES and CEL)

• Treatment options:
  • Cytotoxic chemotherapy
  • Hematopoietic stem cell transplantation 2

Monitoring and Follow-up

• Regular monitoring of eosinophil counts
• Assessment for resolution of symptoms
• Vigilance for end-organ damage, particularly cardiac complications
• Regular assessment of organ function 1

Important Caveats

• For mild eosinophilia (<1.5 × 10^9/L) without symptoms or organ involvement, a watch-and-wait approach with close follow-up may be appropriate 2
• The goal of therapy is to mitigate eosinophil-mediated organ damage, which can be irreversible and life-threatening if left untreated 3
• Identification of specific genetic rearrangements (especially PDGFRA or PDGFRB) is critical due to excellent response to targeted therapy 2
• Long-term therapy is often required, especially for idiopathic hypereosinophilic syndrome 1
• Cardiac complications require particular vigilance as they can lead to significant morbidity and mortality 1