A broad spectrum of disorders, vasculitis is characterized by inflammation and necrosis of blood vessels. Its clinical effects depend on the vessels involved and reflect tissue ischemia caused by blood flow obstruction.
The prognosis is also variable. For example, hypersensitivity vasculitis is usually a benign disorder limited to the skin, but more extensive polyarteritis nodosa can be rapidly fatal.
Vasculitis can occur at any age, except for mucocutaneous lymph node syndrome, which occurs only during childhood. Vasculitis may be a primary disorder or secondary to other disorders, such as rheumatoid arthritis or systemic lupus erythematosus. (See Types of vasculitis, pages 896 to 899.)
Types of vasculitis
|Type||vessels involved||peak age at onset (years)||Male: Female ratio||signs and symptoms||diagnosis|
|Polyarteritis nodosa (PAN)||Small- to medium-sized arteries throughout body. Lesions tend to be segmental, occur at bifurcations and branchings of arteries, and spread distally to arterioles. In severe cases, lesions circumferentially involve adjacent veins. They do not involve arterioles or venules.||40 to 60||2:1||Hypertension, abdominal pain, myalgias, headache, joint pain, weakness, weight loss, mono- or polyneuropathy||History of symptoms. Elevated BUN and creatinine levels, elevated erythrocyte sedimentation rate (ESR), leukocytosis, anemia, thrombocytosis, depressed C3 complement, rheumatoid factor > 1:60, circulating immune complexes. Tissue biopsy shows necrotizing vasculitis and immune deposits.|
|Allergic angiitis and granulomatosis (Churg-Strauss syndrome)||Small- to medium-sized arteries and small vessels (arterioles, capillaries, and venules), mainly of the lung, kidney, and other organs||40 to 60||2:1||Resembles polyarteritis nodosa with hallmark of severe pulmonary involvement||History of asthma. Eosinophilia, increased serum IgI; tissue biopsy shows granulomatous inflammation with eosinophilic infiltration.|
|Microscopic polyangiitis||Small- to medium-sized arteries and small vessels (arterioles, capillaries, venules) of lung and kidney (different from PAN, in that smaller vessels are involved)||40 to 60||1.8:1||Fever, pulmonary congestion, hemoptysis, hematuria, abnormal urine sediment, weight loss, malaise||Usually involves lung and kidneys, elevated ESR; 50% are positive for pANCA. Tissue biopsy shows necrotizing vasculitis without immune deposits or granuloma formation.|
|Wegener’s granulomatosis||Medium- to large-sized vessels of the upper and lower respiratory tract and kidney; may also involve small arteries and veins||30 to 50||1:1||Fever, pulmonary congestion, cough, malaise, anorexia, weight loss, mild to severe hematuria|