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

Management of Eosinophilia

The appropriate treatment for eosinophilia depends critically on identifying the underlying cause through systematic evaluation, with helminth infections requiring empiric antiparasitic therapy in endemic-exposed patients, hypereosinophilic syndrome requiring corticosteroids as first-line treatment, and myeloid neoplasms with PDGFRA/PDGFRB rearrangements requiring imatinib. 1, 2, 3

Initial Risk Stratification

Immediate hematology referral is mandatory for any patient presenting with:

• Absolute eosinophil count ≥5.0 × 10⁹/L at any time 4
• Eosinophil count ≥1.5 × 10⁹/L persisting >3 months after infectious causes excluded 4, 3
• Any evidence of end-organ damage (cardiac, pulmonary, neurologic, gastrointestinal, or dermatologic involvement) regardless of eosinophil level 4, 2

Urgent cardiac evaluation is critical in patients with hypereosinophilia and any cardiac symptoms (chest pain, dyspnea, heart failure symptoms, arrhythmias), as eosinophilic cardiac disease can cause irreversible fibrosis. 4, 5

Diagnostic Algorithm by Clinical Context

For Patients with Travel History to Endemic Regions

Helminth infection accounts for 19-80% of eosinophilia cases in returning travelers and must be excluded first. 1, 6, 4

Obtain these specific tests immediately:

• Three separate concentrated stool specimens for ova and parasites 1, 6
• Strongyloides serology (critical because this parasite persists lifelong and causes fatal hyperinfection syndrome if immunosuppression occurs later) 1, 6, 4
• Schistosomiasis serology if freshwater exposure in Africa or tropical regions 1, 6

Empiric treatment should be initiated while awaiting results in symptomatic patients with travel history:

• Albendazole 400 mg single dose PLUS ivermectin 200 μg/kg single dose 6
• If schistosomiasis suspected: praziquantel 40 mg/kg single dose, repeated at 6-8 weeks 6

Critical warning: Never initiate corticosteroids before excluding Strongyloides, as steroids precipitate fatal hyperinfection syndrome in undiagnosed strongyloidiasis. 6, 4

For Patients with Gastrointestinal Symptoms

Eosinophilic esophagitis requires endoscopic diagnosis in patients presenting with dysphagia or food impaction, as peripheral eosinophilia occurs in only 10-50% of adults with this condition. 1, 4

Perform upper endoscopy with multiple biopsies (minimum 6 biopsies: 2-3 from proximal and 2-3 from distal esophagus). 1

First-line treatment for confirmed eosinophilic esophagitis:

• Topical swallowed corticosteroids (fluticasone or budesonide) are the primary therapy 1, 7
• Alternative: Proton pump inhibitors (omeprazole 20 mg twice daily for 8-12 weeks) 7
• Histological remission is defined as <15 eosinophils per 0.3 mm² 4

Maintenance therapy is mandatory after achieving remission, as clinical relapse rates are high after topical steroid withdrawal. 1

Endoscopic dilation is safe and effective for fibrostenotic disease, but must be combined with anti-inflammatory therapy for optimal outcomes. 1

For Patients Without Travel History or GI Symptoms

Systematic evaluation for primary eosinophilic disorders is required:

Obtain these diagnostic tests:

• Peripheral blood morphology and bone marrow examination 2, 3
• Flow cytometry and cytogenetics to detect myeloid neoplasms 2, 3
• Molecular testing for PDGFRA, PDGFRB, FGFR1, and PCM1-JAK2 rearrangements 2, 3
• T-cell clonality assessment to identify lymphocyte-variant hypereosinophilia 2, 3
• Serum tryptase and vitamin B12 (elevated in myeloproliferative disorders) 2

Screen for end-organ damage in all patients with eosinophil count >1.5 × 10⁹/L:

• Cardiac: ECG, troponin, NT-proBNP, echocardiography 4, 5
• Pulmonary: chest X-ray, pulmonary function tests 4
• Neurologic: EMG if peripheral neuropathy suspected 4

Treatment by Specific Diagnosis

Myeloid Neoplasms with PDGFRA/PDGFRB Rearrangements

Imatinib is the definitive treatment with exquisite responsiveness. 2, 8, 3

Dosing:

• Standard dose: 400 mg daily 5, 2
• For FIP1L1-PDGFRA fusion: start at 100 mg daily (lower dose due to high sensitivity), may increase to 400 mg if insufficient response 5

Special precaution for hypereosinophilic syndrome with cardiac involvement: Consider prophylactic systemic corticosteroids (1-2 mg/kg) for 1-2 weeks when initiating imatinib, as HES cell degranulation can cause cardiogenic shock. 5

Idiopathic Hypereosinophilic Syndrome (HES)

Corticosteroids are first-line therapy. 2, 8, 3

Treatment algorithm:

• Initial: Prednisone 1 mg/kg daily until eosinophil count normalizes 2, 8
• Taper gradually while monitoring eosinophil counts 2
• For steroid-refractory cases: hydroxyurea or interferon-alpha 2, 8, 3
• For steroid-dependent cases: mepolizumab (anti-IL-5 antibody) is FDA-approved for idiopathic HES 3

Lymphocyte-Variant Hypereosinophilia

Corticosteroids are first-line therapy for this aberrant T-cell clone-driven reactive eosinophilia. 2, 8, 3

Chronic Eosinophilic Leukemia (CEL, NOS)

Hydroxyurea is initial treatment for this aggressive myeloproliferative neoplasm. 2, 8

Second-line options include:

• Cytotoxic chemotherapy 2, 8
• Hematopoietic stem cell transplantation for eligible patients 2, 8, 3

Monitoring Strategy

For mild eosinophilia (<1.5 × 10⁹/L) without organ involvement: Watch-and-wait approach with close follow-up is appropriate. 2, 8, 3

For treated patients:

• Repeat complete blood count 2-4 weeks post-treatment to assess eosinophil count response 6
• Repeat endoscopy with biopsies if symptoms recur during treatment for eosinophilic esophagitis 1
• Monitor for treatment-related complications (corticosteroid side effects, imatinib hepatotoxicity) 1, 5

Critical Pitfalls to Avoid

Never assume normal imaging excludes helminth infection, as many parasitic infections cause eosinophilia without radiographic abnormalities, especially in early stages. 6, 4

Never rely solely on peripheral eosinophil counts to assess tissue eosinophilia in conditions like eosinophilic esophagitis—tissue biopsy is the gold standard. 1, 4

Never delay cardiac evaluation in patients with hypereosinophilia and any cardiac symptoms, as eosinophilic myocarditis can progress rapidly to irreversible fibrosis. 4, 5

Refractory cases require multidisciplinary management with gastroenterology, hematology, and allergy/immunology specialists, particularly when significant concomitant atopic disease exists. 1, 4