vasculitis

Vasculitis refers to a heterogeneous group of disorders characterized by inflammation of blood vessel walls. The inflammatory process can affect any vessel type and size, potentially narrowing or blocking blood flow and causing organ ischemia, aneurysm, or rupture. It can be primary or secondary to infections, drugs, or systemic diseases.

Vasculitis is commonly classified by vessel size: large-vessel vasculitis (eg, giant cell arteritis, Takayasu arteritis), medium-vessel vasculitis (eg, polyarteritis nodosa, Kawasaki disease), and small-vessel vasculitis (including ANCA-associated diseases such as granulomatosis with polyangiitis and microscopic polyangiitis, as well as eosinophilic granulomatosis with polyangiitis and anti-GBM disease).

Pathophysiology is often autoimmune, with immune cell infiltration of vessel walls and, in some forms, immune complex deposition or granulomatous inflammation. ANCA antibodies are linked to several small-vessel diseases, while other types may involve immune complexes or direct vessel injury.

Clinical features vary by vessel involved. Large-vessel disease may cause limb claudication, diminished pulses, or carotid bruits and can present with headaches and jaw claudication in giant cell arteritis. Medium-vessel disease can cause mesenteric or renal ischemia; small-vessel disease often presents with systemic symptoms and organ involvement such as kidneys or lungs and palpable purpura.

Diagnosis relies on clinical assessment supported by laboratory tests (erythrocyte sedimentation rate or C-reactive protein), serology such as ANCA, imaging (CTA/MRA, ultrasound, or angiography), and tissue biopsy showing inflammatory infiltrates and sometimes necrosis.

Treatment is tailored to disease type and severity. First-line therapy typically includes corticosteroids; additional immunosuppressants such as cyclophosphamide, methotrexate, azathioprine, or rituximab are used for longer-term control. In some conditions, plasmapheresis or biologic agents may be employed, with careful attention to infection risk and cardiovascular protection.

Prognosis varies; untreated systemic vasculitis can be life-threatening, but many patients achieve remission with therapy. Relapses are common, necessitating ongoing follow-up and sometimes long-term immunosuppression.