What is the appropriate management for a patient with lymphocytosis and eosinophilia?

Management of Lymphocytosis and Eosinophilia

The appropriate management for a patient with lymphocytosis and eosinophilia requires a systematic diagnostic approach followed by targeted treatment, with empiric treatment with albendazole plus ivermectin being the first-line intervention for asymptomatic cases in returning travelers or migrants.

Diagnostic Approach

Step 1: Evaluate for Common Infectious Causes

• Parasitic infections: Most common identifiable cause in returning travelers/migrants
  • Helminth infections (strongyloidiasis, schistosomiasis, filariasis) 1
  • Consider travel history, especially to endemic areas
  • Look for specific symptoms: skin rash, respiratory symptoms, abdominal pain

Step 2: Rule Out Non-Infectious Causes

• Drug reactions:

  • DRESS syndrome (Drug Reaction with Eosinophilia and Systemic Symptoms) 2
  • Review all medications started within past 2-3 weeks

• Hematologic malignancies:

  • Myeloid/lymphoid neoplasms with eosinophilia and TK fusion genes 1
  • Look for symptoms of weakness, fatigue, cough, dyspnea, rash, fever

• Autoimmune disorders:

  • Autoimmune hemolytic anemia may present with eosinophilia 3
  • Check for signs of hemolysis (jaundice, elevated indirect bilirubin)

Step 3: Diagnostic Testing

1. Complete blood count with differential
2. Peripheral blood smear - to assess for atypical lymphocytes, blast cells
3. Stool examination for ova and parasites (3 samples)
4. Serologic testing for parasitic infections based on travel history
5. Chest imaging if respiratory symptoms present
6. Organ-specific testing based on symptoms:
   • Liver function tests if hepatomegaly or abdominal symptoms
   • Cardiac evaluation if chest pain or dyspnea

Treatment Algorithm

For Asymptomatic Patients with Travel History

1. Empiric antiparasitic therapy:
   • First-line: Albendazole 400 mg single dose PLUS ivermectin 200 μg/kg single dose 1
   • This approach is recommended for those >24 months of age with travel history

For Symptomatic Patients

1. If parasitic infection confirmed:

   • Strongyloidiasis: Ivermectin 200 μg/kg daily for 2 days 1
   • Schistosomiasis: Praziquantel 40 mg/kg in 2-3 divided doses for 1 day 1
   • Filariasis: Seek specialist advice before using diethylcarbamazine (DEC) due to risk of severe reactions 1

2. If drug reaction suspected:

   • Discontinue the offending medication
   • For severe reactions (DRESS syndrome): High-dose corticosteroids 2

3. If hematologic malignancy suspected:

   • Urgent referral to hematology
   • Bone marrow examination may be required
   • Genetic testing for TK fusion genes if myeloid/lymphoid neoplasm with eosinophilia suspected 1

Special Considerations

Severity Assessment

• High-risk features requiring urgent intervention:
  • Eosinophil count ≥1.5 × 10⁹/L for >3 months 1
  • Evidence of end-organ damage (cardiac, pulmonary, neurological)
  • Rapidly rising eosinophil count

Monitoring

• Follow-up CBC at 2-4 weeks after treatment
• If eosinophilia persists despite treatment, consider:
  • Alternative diagnoses
  • Treatment failure
  • Referral to hematology if eosinophilia ≥1.5 × 10⁹/L persists for >3 months 1

Pitfalls to Avoid

1. Don't assume all eosinophilia is parasitic - drug reactions and hematologic malignancies are important causes
2. Don't miss hyperinfection syndrome in strongyloidiasis - can be fatal in immunocompromised patients
3. Don't use diethylcarbamazine (DEC) without specialist input - can cause severe reactions in patients with onchocerciasis or high Loa loa microfilaremia 1
4. Don't forget to consider drug-induced causes - many medications can cause eosinophilia with or without systemic symptoms

By following this structured approach, most cases of lymphocytosis and eosinophilia can be effectively diagnosed and managed, with improved patient outcomes and reduced risk of complications.