17th January 2024

Differential diagnoses

A number of conditions can present similarly to EGPA, including those that also present with eosinophilia. Some of these conditions and their key differences to EGPA are summarised below.

1. Hypereosinophilic syndrome (HES) – in HES, asthma and vasculitis complications do not occur. Additionally, specific gene mutations can be tested for that can be present in HES but would not be present in EGPA.
2. Allergic bronchopulmonary aspergillosis (ABPA) – ABPA does not present with vasculitis and tends to affect only the upper and lower airways rather than any other organ systems. Positive allergy and specific serum IgE testing for Aspergillosis fumigatus would support a diagnosis of ABPA over EGPA.
3. Microscopic polyangiitis (MPA) – asthma and peripheral eosinophilia are absent, as are lung infiltrates and nodules. Lung function is usually normal.
4. Granulomatosis with polyangiitis (GPA) – GPA does not present with asthma; lung function will likely be normal. Additionally, alveolar haemorrhage and glomerulonephritis are common in GPA but not in EGPA. Those with GPA are likely to have a positive c-ANCA/PR3-ANCA result, compared to those with EGPA, who tend to have a positive p-ANCA/MPO-ANCA result instead.