Lesson of the month: Severe granulomatosis with polyangiitis (GPA): a diagnostic challenge during the COVID-19 pandemic.

We present the case of a 71-year-old woman with bilateral pneumonia who continued to deteriorate despite multiple courses of antibiotics. When dexamethasone was added to cover the possibility of COVID-19 pneumonia, she rapidly improved. Subsequently, she was found to have a strongly positive PR3 anti-nuclear cytoplasmic antibody (ANCA) and clinical features consistent with granulomatosis with polyangiitis (GPA) with upper respiratory tract and renal involvement. The case highlights how the COVID-19 pandemic can create new challenges in the diagnosis of GPA. © Royal College of Physicians 2021. All rights reserved.