Anti-neutrophil cytoplasmic antibody (ANCA)-associated vasculitides (AAV) usually affect adults and older populations. The well recognized clinical (i.e., granulomatosis with polyangiitis [GPA], microscopic polyangiitis, and eosinophilic GPA) and serological phenotypes (i.e., anti-MPO-ANCA, anti-PR3-ANCA and ANCA negative) within AAV differ substantially for clinical, demographic, and epidemiological features, including age at presentation. Whether and how aging could contribute to the clinical expression of these disease phenotypes is intriguing and still overlooked. In addition, despite being predominantly a disease of the elderly, most of the studies analyzing drug interventions and the clinical trials on AAV explicitly excluded older pa...