The primary vasculitidies are complex diseases with varied clinical manifestations, which may be common to those present in multiple diseases. The antineutrophil cytoplasm autoantibodies (ANCA) led to a revolution in the diagnosis and research of these diseases, being the first and so far, the only biomarkers for three of these diseases, which affect small caliber vessels. From their descriptio...

Autoantibodies against various “self” intraor extracellular, cell surface-bound or soluble antigens are frequently present in the sera of patients with autoimmune diseases. Regardless of their precise role in the pathogenesis of these diseases, testing for autoantibodies constitutes an integral part of the initial diagnostic workup of patients with organ-specific or systemic autoimmune diseases...

Accumulating in vivo and in vitro evidence supports the hypothesis that antineutrophil cytoplasm autoantibodies (ANCA) with specificity for proteinase 3 (PR3) and myeloperoxidase (MPO) are involved in the pathophysiology of small-vessel vasculitis. The best-described effector function of these autoantibodies is stimulation of neutrophils to produce reactive oxygen species and to release proteol...

Antineutrophil cytoplasmic antibody (ANCA)–associated vasculitis encompasses 3 conditions: eosinophilic granulomatosis with polyangiitis (EGPA; formerly named Churg-Strauss syndrome), granulomatosis with polyangiitis (GPA; formerly named Wegener granulomatosis), and microscopic polyangiitis.1 Diagnosing ANCA-associated small-vessel vasculitis is challenging for clinicians because of its infrequ...

Antineutrophil cytoplasmic antibody (ANCA)-associated vasculitis (AAV) is a rare heterogeneous disease in which treatment must be initiated early to prevent irreversible organ damage and death. There are several diseases that can mimic AAV, even the presence of positive ANCA serology and/or histological evidence vasculitis, as demonstrated this case series. We reflect on diagnostic approach pat...