Refractory PR3-positive ANCA-associated vasculitis with eosinophilia requiring anti-IL-5 therapy: A case report

This report describes a highly unusual and refractory case of proteinase-3-positive antineutrophil cytoplasmic autoantibody-associated vasculitis, which was associated with marked eosinophilia and only achieved remission after interleukin-5 blockade was added to maximal induction therapy. The patient was a healthy 18-year-old woman who presented with scleritis, otitis, constitutional symptoms, skin and mucosal lesions, and diffuse alveolar haemorrhage and found to have refractory eosinophilia of unclear aetiology. The case did not meet classification criteria for a diagnosis of granulomatosis with polyangiitis or eosinophilic granulomatosis with polyangiitis. Despite induction therapy with glucocorticoids, cyclophosphamide, and rituximab, she did not achieve remission or normalisation of eosinophilia until the addition of mepolizumab, which corresponded to the suppression of peripheral blood eosinophils and clinical remission. This case highlights the limitations of classification criteria and success of interleukin-5 in a multimodal treatment of severe vasculitis with eosinophilia.