Vasculitides

Vasculitides are a group of disorders characterized by inflammation of blood vessel walls, which can lead to vessel damage and reduced blood flow to various organs. The disease spectrum is broad and can involve vessels of any size, from large arteries to small capillaries, and may present with a wide range of symptoms depending on the organs affected.

Most classifications group vasculitides by the size of the affected vessels: large vessel, medium vessel, and small vessel. Large-vessel forms include giant cell arteritis and Takayasu arteritis, which primarily affect the aorta and its major branches. Medium-vessel diseases include polyarteritis nodosa and Kawasaki disease, which affect medium-sized arteries and can involve coronary vessels in children. Small-vessel vasculitides are heterogeneous and include ANCA-associated vasculitides—granulomatosis with polyangiitis (formerly Wegener’s), microscopic polyangiitis, and eosinophilic granulomatosis with polyangiitis (Churg–Strauss)—as well as immune complex–mediated diseases such as IgA vasculitis (Henoch–Schönlein purpura) and cryoglobulinemic vasculitis. Thromboangiitis obliterans (Buerger disease) is often considered a small- to medium-vessel process linked to tobacco use.

Clinical presentation is variable and may include constitutional symptoms (fever, weight loss), fever of unknown origin, and organ-specific signs such as kidney impairment, pulmonary hemorrhage, skin purpura, abdominal pain, neuropathy, or claudication. Diagnosis relies on clinical assessment, laboratory tests (including inflammatory markers and, in many cases, ANCA testing), imaging, and tissue biopsy, which remains the diagnostic gold standard in many forms.

Treatment centers on immunosuppression to control vessel inflammation, typically starting with corticosteroids and adding steroid-sparing agents (such as cyclophosphamide, methotrexate, azathioprine, or rituximab) for sustained remission. Management also emphasizes minimizing relapses and monitoring for organ damage, with prognosis varying by phenotype and promptness of treatment.