What focused history should be obtained for an asthmatic patient with an absolute eosinophil count of 2350 cells/µL to evaluate for eosinophilic granulomatosis with polyangiitis (EGPA) or hypereosinophilic syndrome (HES)?

Focused History for Asthmatic Patient with Eosinophilia (2350 cells/µL)

In an asthmatic patient with an absolute eosinophil count of 2350 cells/µL, immediately obtain a detailed history focusing on: duration and severity of asthma, presence of chronic rhinosinusitis with nasal polyps, any neurological symptoms (numbness, tingling, weakness), cardiac symptoms (chest pain, dyspnea beyond asthma), skin lesions, gastrointestinal symptoms, constitutional symptoms, and environmental/occupational exposures to distinguish EGPA from other hypereosinophilic disorders.

Critical Historical Elements to Elicit

Respiratory History

• Asthma characteristics: Age of onset, severity progression, response to conventional therapy, and whether asthma has worsened over time 1
• Duration of asthma: EGPA typically develops after years of asthma (median 10 years in one cohort), with asthma often becoming more severe and refractory 2
• Upper airway involvement: Chronic rhinosinusitis with nasal polyps (present in 60-80% of EGPA), history of recurrent polyps after surgical excision, otitis media 1
• Pulmonary infiltrates: History of migratory lung infiltrates that respond to corticosteroids 1

Neurological Symptoms (Critical Red Flag)

• Peripheral neuropathy: Numbness, tingling, burning sensations, or weakness in extremities (occurs in 50-70% of EGPA) 1
• Pattern: Mononeuritis multiplex is characteristic - asymmetric involvement of multiple individual nerves
• Motor deficits: Foot drop, wrist drop, or other focal motor weakness 1

Cardiac Symptoms (Life-Threatening Manifestations)

• Cardiac involvement: Chest pain, palpitations, dyspnea beyond what asthma explains, syncope 1
• Note: Cardiac involvement is more common in ANCA-negative EGPA and is a major cause of mortality 1

Dermatological History

• Skin lesions: Palpable purpura (most specific for vasculitis), nodules, urticaria, livedo reticularis 1
• Distribution and timing: When lesions appeared relative to asthma onset

Gastrointestinal Symptoms

• GI involvement: Abdominal pain, diarrhea, bloody stools, nausea (more common in ANCA-negative EGPA) 1

Constitutional Symptoms

• Systemic features: Fever, weight loss, fatigue, myalgias, arthralgias 1
• Timing: When these symptoms developed relative to asthma

Environmental and Medication History

• Exposures: Silica, organic solvents, farming (associated with increased EGPA risk) 1
• Smoking history: Paradoxically, smoking is associated with lower EGPA risk 1
• Leukotriene inhibitor use: Document if patient is on these medications (historically associated with EGPA unmasking, though causality debated) 3
• Corticosteroid use: Previous or current use may mask eosinophilia 1

Renal Symptoms

• Kidney involvement: Hematuria, proteinuria, edema, reduced urine output (more common in ANCA-positive EGPA) 1

Differential Diagnosis Considerations

Key Historical Distinctions

• HES vs EGPA: HES lacks the characteristic asthma-rhinosinusitis prodrome and vasculitic features 1, 4
• Parasitic infections: Travel history, exposure to endemic areas
• Allergic bronchopulmonary aspergillosis (ABPA): Typically has very high IgE levels (unlike EGPA) and specific IgE to Aspergillus 5
• Other vasculitides: GPA typically lacks prominent asthma and eosinophilia 1

Temporal Pattern Assessment

EGPA typically evolves through phases (though these may overlap) 1:

1. Prodromic "allergic" phase: Asthma and chronic rhinosinusitis (can last years)
2. Eosinophilic phase: Peripheral eosinophilia with organ infiltration
3. Vasculitic phase: Mononeuritis multiplex, glomerulonephritis, purpura

Document where the patient appears to be in this progression.

Critical Pitfalls to Avoid

• Don't dismiss eosinophilia as "just asthma": Eosinophilia >1,500 cells/µL in asthma should trigger evaluation for EGPA 1
• Don't overlook subtle neuropathy: Patients may not volunteer paresthesias unless specifically asked
• Don't miss cardiac involvement: This is the leading cause of death in EGPA and may be subclinical initially 6
• Don't assume ANCA negativity excludes EGPA: 60-70% of EGPA patients are ANCA-negative 1

Next Steps After History

Based on history findings, proceed with:

• ANCA testing (MPO-ANCA and PR3-ANCA) in all suspected cases 1
• Echocardiogram at diagnosis to screen for cardiac involvement 3
• Nerve conduction studies if any neurological symptoms present
• Urinalysis for hematuria/proteinuria
• Chest imaging for infiltrates
• Consider cardiac ECT (more sensitive than routine cardiac tests) 6