What are the key clinical features to consider when diagnosing Eosinophilic Granulomatosis with Polyangiitis (EGPA) in a patient presenting with respi

Key clinical features to consider when diagnosing Eosinophilic Granulomatosis with Polyangiitis (EGPA) in a patient presenting with respiratory symptoms include:

• Asthma and allergic rhinitis: A history of adult-onset asthma, often severe and difficult to control, is a hallmark feature preceding other manifestations in EGPA NICE NG115 Choi et al. 2019.
• Peripheral blood eosinophilia: Marked eosinophilia in peripheral blood is a critical diagnostic clue, reflecting eosinophilic inflammation characteristic of EGPA NICE NG115 Cottin 2016.
• Respiratory symptoms: These include wheezing, cough, dyspnoea, and sometimes pulmonary infiltrates visible on imaging, which may mimic asthma exacerbations or eosinophilic pneumonia NICE NG115 Cottin 2016.
• Systemic vasculitic features: Although respiratory symptoms predominate, clinicians should assess for signs of small to medium vessel vasculitis such as palpable purpura, mononeuritis multiplex, or constitutional symptoms, which support EGPA diagnosis NICE NG115 Choi et al. 2019.
• Extravascular eosinophilic granulomas: Tissue biopsy, if performed, may reveal eosinophilic-rich granulomatous inflammation, aiding diagnosis NICE NG115 Choi et al. 2019.
• ANCA status: Anti-neutrophil cytoplasmic antibodies (ANCA), particularly MPO-ANCA, may be positive in a subset of patients and can help differentiate EGPA from other eosinophilic lung diseases, though ANCA-negative cases are common NICE NG115 Choi et al. 2019.
• Exclusion of mimics: Given overlapping features with COVID-19 and other eosinophilic lung diseases, careful clinical and laboratory evaluation is essential to avoid misdiagnosis Özdemir et al. 2021.

In summary, the diagnosis of EGPA in patients with respiratory symptoms relies on recognizing adult-onset asthma with marked eosinophilia, systemic vasculitic signs, and supportive serology or histology, while excluding other causes of eosinophilic lung disease NICE NG115 Cottin 2016Choi et al. 2019Özdemir et al. 2021.