The vasculitides are a group of systemic disorders with vessel inflammation and myriad clinical presentations. There are many systems used to categorize them. The system below is based largely on the size of the vessels involved.
Takayasu arteritis occurs in older adults (age >50). Initial symptoms may be non-specific (fatigue) with a variable course to more severe symptoms (blindness) and involvement of the aortic arch. Microscopically, there is vessel wall thickening and variable inflammation (from a mononuclear adventitial infiltrate to medial necrosis with granulomas).
Giant cell arteritis was formerly called temporal arteritis, but the temporal arteriesare not always involved. The vertebral and ophthalmic arteries and aorta are often involved. The typical presentation evolves from nonspecific symptoms (headache) to more severe symptoms (blindness). Microscopically, there are inner media granu-lomas in classic cases. Treatment is steroids and anti-TNF therapy.
Kawasaki disease presents with mucocutaneous symptoms and cervical lymph nodeenlargement in children. Involvement of the coronary arteries leads to cardiovascu-lar sequelae, which can be circumvented with immunoglobulin therapy. Microscopi-cally, there is transmural vascular inflammation.
Polyarteritis nodosa is a systemic necrotizing vasculitis occurring most often inyoung adults (M > F). It has an association with hepatitis B virus. The clinical course is one of episodic nonspecific symptoms (low-grade fever). Pulmonary involve-ment is rare; renal artery involvement can be fatal. Immunosuppressive therapy can achieve remission in most cases.
Small vessel vasculitides include those that are ANCA (antineutrophil cytoplasmic antibody)-associated (granulomatosis with polyangiitis, formerly known as Wegen-er’s granulomatosis; and eosinophilic granulomatosis with polyangiitis, formerly known as Churg-Strauss syndrome) and those that are mediated by immune com-plexes (e.g., anti-glomerular basement membrane disease and IgA vasculitis, also known as Henoch-Schönlein purpura).
Granulomatosis with polyangiitis typically occurs in middle-aged men; it is charac-terized by granulomas of the lung and upper respiratory tract, glomerulonephritis, and a necrotizing granulomatous vasculitis. PR3-ANCAs are present in most cases.
Eosinophilic granulomatosis with polyangiitis is associated with asthma, extravas-cular granulomas (respiratory tract), and a systemic vasculitis that features eosino-phils; eosinophil counts may be extremely high in peripheral blood. T lymphocytes and antibodies to MPO (P-ANCA) play a role in the etiology. There may be increased IgG4 levels. ANCA is present in cases with glomerulonephritis. The sequential phases are allergic, followed by eosinophilic and vasculitic. Cardiac involvement may be fatal. Steroids are therapeutic. Microscopic findings depend upon the organ biopsied: Purpuric leg lesions show a leukocytoclastic vasculitis; the glomerulo-nephritis tends not to show eosinophilic infiltrates; the extravascular pulmonary granulomas contain eosinophils.
Other small vessel vasculitides include variable vessel vasculitides, e.g., Behcet’s disease; single organ vasculitides, e.g., CNS vasculitides; and vasculitis associatedwith systemic disease, e.g., rheumatoid vasculitis.