Pauciimmune vasculitis

Pauciimmune vasculitis encompasses a group of systemic necrotizing vasculitis with paucity of immune complex deposition on microscopic examination. All these diseases have anti-neutrophil cytoplasmic antibody (ANCA) positivity, hence, also termed as ANCA associated vasculitides. It encompasses a spectrum of small vessel vasculitis; granulomatosis with polyangiitis (GPA), microscopic polyangiitis (MPA) and eosinophilic granulomatosis with polyangiitis (EGPA). Activated neutrophils (and eosinophils in EGPA) resulting from known and unknown environmental influences on a susceptible genetic background cause vascular injury in various organ systems. The spectrum of disease extends from involvement of upper and lower respiratory tracts to life threatening renal and nervous system involvement. High index of suspicion and early diagnosis and initiation of immunosuppression therapy is crucial for minimizing the risk of morbidity and mortality.