Chest CT findings in both diseases may show ground-glass opacities and diffuse alveolar hemorrhage.[9] A Spanish survey reported an average diagnostic delay of up to 3 months for these patients, with about 6% experiencing a delay exceeding 1 year.[7] Accurately diagnosing AAV, assessing disease severity, and distinguishing between active vasculitis, infection, and other complications or comorbidities remains challenging.[10] Although MPO-ANCA is found in both MPA and EGPA, several clinical features distinguish the 2 conditions. This evidence concerns the gene MPO and eosinophilic granulomatosis with polyangiitis.