Wegener's granulomatosis and microscopic polyangiitis

Wegener's granulomatosis (WG) and microscopic polyangiitis (MPA) are primary systemic small vessel vasculitides, associated with a positive C/PR3-ANCA in WG and P/MPO-ANCA in MPA. The most prominently involved organs are the upper (only in WG) and lower respiratory tract and the kidneys. The diagnostic work-up is an interdisciplinary approach assessing disease stage and extent. Treatment is adapted to disease stage and extent and relies on a combination of a cytotoxic plus a tapering regimen of corticosteroids. Induction of remission in "early systemic" disease can be achieved with low-dose methotrexate. In severe generalized vasculitis cyclophosphamide (CYC) is the mainstay of therapy, in rapidly progressive glomerulonephritis in combination with plasmapheresis. After 3-6 months of induction CYC is switched to a maintenance treatment with azathioprine. Alternatives are leflunomide, mycophenolate or methotrexate (creatinine < 150 mu mol/l). Age >= 50 at diagnosis, renal dysfunction and pulmonary involvement are associated with higher mortality rates. The relapse rate is approximately 50% within 5 years, being higher in WG than MPA.