polyarteritis nodosa

necrotizing vasculitis of medium-sized arteries

usually in male adults
associated with hepatitis B antigen
kidney: most frquently involved organ (85%)
- multiple small intrarenal aneurysms
- aneurysms may disappear (thrombosis) or appear in new locations
- arterial narrowing and thrombosis (chronic/healing stage)
- multiple small cortical infarcts
- associated with hypertension and renal failure
chest involvement (70%)
- cardiomegaly/pericardial effusion (14%)
- wedge shaped/round peripheral infiltrates simulating PE (14%)
- interstitial lower lung field pneumonitis
also may involve liver (66%), mesenteric vessels (50%), skeletal muscle (39%), skin (20%)