Wegener’s granulomatosis (WG) is the systemic vasculitis of small and medium arteries, venules, and arterioles. Large arteries may also be affected.

WG is rare; the exact frequency is not known. Recent estimates of incidence put the occurrence at 1:30,000 to 1:50,000 individuals. The age of onset peaks at 40 to 50 years, and it appears equally in males and females, with a strong predilection for Caucasians (>97% of cases).

The exact cause of WG is still unknown. Antineutrophilic cytoplasmic antibody (ANCA) has been detected in most cases, and the concentration seems to correlate with the severity of the disease.

Triad of physiologic features of Wegener’s granulomatosis.

Wegener’s Granulomatosis. The lung parenchyma contains two nodulesshowing central necrosis.