Microscopic Polyangiitis

Microscopic polyangiitis (MPA) belongs to the antineutrophil cytoplasmic autoantibody (ANCA)-associated vasculitides (AAVs). MPA is clinically characterized by small-vessel vasculitis primarily affecting the kidneys and the lungs, but other organs may be involved as well. Renal involvement is clinically apparent as rapidly progressive glomerulonephritis and histopathologically as pauci-immune necrotizing and crescentic glomerulonephritis. ANCAs in MPA are mainly directed to myeloperoxidase (MPO-ANCA). The first formal classification criteria for MPA have been recently established. Induction treatment consists of cyclophosphamide or rituximab and glucocorticoids followed by maintenance therapy. A new targeted treatment, avacopan, has recently been approved.