Wegener's granulomatosis is a rare autoimmune disorder that occurs when a person's defense (immune) system attacks its own tissues as if they were foreign substances. It usually begins as an inflammation of the upper and lower respiratory tract and then progresses to inflammation of the blood vessels (vasculitis) and inflammation of the filters in the kidneys (glomerulonephritis).

Wegener's granulomatosis may also affect the skin, joints, eyes, and nervous system. The cause of the disease is unknown.

Corticosteroids and other medicines that suppress the immune system may be used to treat this disease. Doctors sometimes use plasma exchange (plasmapheresis) to treat severe cases.