What is the treatment for a patient with diffuse pruritis and eosinophilia on Complete Blood Count (CBC)?

Treatment for Diffuse Pruritus with Eosinophilia on CBC

The treatment for diffuse pruritus with eosinophilia should first focus on identifying and treating the underlying cause, with empirical therapy of albendazole 400 mg plus ivermectin 200 μg/kg as first-line treatment for possible helminth infection in patients with travel history to endemic regions. 1

Step 1: Determine the Underlying Cause

Common Causes of Eosinophilia with Pruritus:

• Parasitic infections: Particularly helminth infections such as strongyloidiasis, schistosomiasis, hookworm, and filariasis 1
• Drug reactions: Review all medications for potential hypersensitivity reactions 1
• Hematologic disorders: Including lymphoma, polycythemia vera, and hypereosinophilic syndromes 1
• Immune-related adverse events: Particularly in patients on immune checkpoint inhibitors 1
• Liver or kidney disease: Cholestatic pruritus and uremic pruritus 1

Step 2: Diagnostic Workup

• Travel history: Essential to guide testing for parasitic infections 1
• Complete blood count: To confirm and quantify eosinophilia 1
• Stool studies: Concentrated stool microscopy and PCR for parasites 1
• Serologic testing: Particularly for strongyloidiasis and schistosomiasis 1
• Skin biopsy: Consider if autoimmune skin disease is suspected 1

Step 3: Treatment Based on Cause

For Parasitic Infections:

• Empiric treatment: For patients with travel history to endemic regions and negative initial workup 1

  • Albendazole 400 mg single dose plus ivermectin 200 μg/kg single dose 1
  • Exclude Loa loa infection before administering ivermectin in patients who have traveled to endemic regions 1

• Specific parasitic treatments:

  • Schistosomiasis: Praziquantel 40 mg/kg as single dose, repeated at 6-8 weeks 1
  • Hookworm: Albendazole 400 mg as a single dose 1
  • Strongyloidiasis: Ivermectin 200 μg/kg daily for 1-2 days 1
  • Pinworm: Albendazole 400 mg or mebendazole 100 mg as a single dose 1

For Hematologic Causes:

• Polycythemia vera-associated pruritus: 1

  • Cytoreductive therapy, aspirin, or interferon-α
  • Consider UVB phototherapy for temporary relief
  • Paroxetine (selective serotonin reuptake inhibitor) has shown >80% response rate

• Lymphoma-associated pruritus: 1

  • Cimetidine, carbamazepine, gabapentin, or mirtazapine
  • Oral corticosteroids for incurable lymphoma
  • UVB phototherapy for temporary relief

For Immune Checkpoint Inhibitor-Related Pruritus: 1

• Grade 1 (mild): Continue immunotherapy, use topical emollients and mild-moderate potency corticosteroids
• Grade 2 (moderate): Consider holding immunotherapy, use topical emollients, oral antihistamines, medium-high potency topical corticosteroids, consider prednisone 0.5-1 mg/kg
• Grade 3 (severe): Hold immunotherapy, consult dermatology, use high-potency topical corticosteroids, oral prednisone 1 mg/kg/day, consider phototherapy

For Liver Disease-Associated Pruritus: 1

• First-line: Rifampicin
• Second-line: Cholestyramine
• Third-line: Sertraline
• Consider UVB phototherapy

For Uremic Pruritus: 1

• Ensure adequate dialysis, normalize calcium-phosphate balance
• Consider capsaicin cream, topical calcipotriol, or oral gabapentin
• BB-UVB phototherapy is effective for many patients

Step 4: Symptomatic Treatment for Generalized Pruritus of Unknown Origin

• Topical treatments: 1

  • Emollients
  • Topical corticosteroids
  • Topical anti-itch remedies (refrigerated menthol and pramoxine)

• Systemic treatments: 1

  • Oral antihistamines (short-term use)
  • For severe cases: Gabapentin, pregabalin, or mirtazapine
  • Prednisone (or equivalent) at 0.5-1 mg/kg for severe cases 2

• Phototherapy: 1

  • UVB phototherapy can be effective for many forms of pruritus

Important Considerations and Pitfalls

• Avoid long-term sedative antihistamines except in palliative care as they may predispose to dementia 1
• Exclude strongyloidiasis before starting corticosteroids to prevent potentially fatal hyperinfection syndrome 1
• Monitor for treatment side effects, particularly with systemic medications 2
• Reevaluate if no response to empiric therapy, as rare causes may require specialized testing 3, 4
• Consider referral to specialists (infectious disease, hematology, dermatology) for refractory cases 5