Definition of Wegener's granulomatosis:

Wegener's granulomatosis is a rare disorder in which certain blood vessels become swollen and inflamed. The inflammation makes it hard for blood to flow. The disease mainly affects the blood vessels in the nose, sinuses, ears, lungs, and kidneys, although other areas may be involved.

Causes, incidence, and risk factors:

The cause is unknown. Wegener's granulomatosis is thought to be an autoimmune disorder. Arthritis occurs in about half of all those with this disease.

Wegener's granulomatosis is most common in middle-aged adults. It is rare in children, but has been seen in infants as young as 3 months old.