Vasculitis

Vasculitis is inflammation of the walls of blood vessels. The inflamed wall thickens and narrows the lumen, can weaken into aneurysms, and may thrombose entirely — so the downstream consequences are ischemia and organ damage. Because any vascular bed can be involved, presentations range from headache and vision loss to kidney failure, skin lesions, and nerve deficits, usually alongside systemic signs like fever, fatigue, and elevated inflammatory markers.

The standard framework classifies vasculitides by vessel size. Large-vessel disease includes giant cell (temporal) arteritis — the elderly patient with headache, jaw claudication, and blindness risk — and Takayasu arteritis in younger, often Asian women. Medium-vessel disease includes polyarteritis nodosa, classically associated with hepatitis B, and Kawasaki disease in children, with its risk of coronary artery aneurysms. Small-vessel disease includes the ANCA-associated vasculitides, such as granulomatosis with polyangiitis, which combines upper airway, lung, and kidney involvement.

Recognizing vasculitis matters because several forms are medical emergencies: untreated giant cell arteritis can cause permanent blindness, and Kawasaki disease requires prompt treatment to protect the coronary arteries. Most vasculitides are autoimmune and respond to immunosuppression, making early diagnosis the pivotal step.

Vasculitis is a high-yield cardiovascular pathology topic on the USMLE Step 1 exam, which tests matching each vasculitis to its vessel size, demographic, associations (such as hepatitis B with polyarteritis nodosa), and buzzword findings. Allied health exams like the PTCE and CCMA touch the concept through medical terminology — the suffix -itis applied to vascular combining forms.