Masuda S, et al. - Given that disordered regulation of neutrophil extracellular traps (NETs) is critically involved in the pathogenesis of anti-neutrophil cytoplasmic antibody (ANCA)-associated vasculitis (AAV), researchers analyzed formalin-fixed, paraffin-embedded tissue sections for the amount of NETs in AAV vs in diseases that should be distinguished from AAV. They noted necrotizing vasculitis of AAV was more abundant in NETs than non-ANCA-associated vasculitis, or granulomatous angiitis. In necrotizing granulomas of AAV vs in granulomas of sarcoidosis without necrosis, a remarkably greater amount of NETs was found. Despite an equivalent formation of NETs seen in necrotizing granulomas of tuberculosis vs in AAV, the NETs in the former were more susceptible to degradation by DNase I than those in AAV. AAV was characterized by the formation and disordered degradation of NETs in necrotizing lesions, which may be associated with its pathogenesis.