A 45-year-old woman of Asian descent presents with upper limb claudication, diminished radial pulses, and carotidynia. ESR is markedly elevated. Angiography shows skip lesions with stenosis and aneurysmal dilation of the aorta and its major branches. The most likely diagnosis and the primary cell type mediating vascular damage is:
- A Takayasu arteritis: CD4+ Th1 cytotoxic T lymphocytes and NK cells in the adventitia-media junction mediate granulomatous inflammation via perforin/granzyme-mediated killing of vascular smooth muscle cells ✓
- B Giant cell (temporal) arteritis: CD4+ Th1 and Th17 cells mediate granulomatous inflammation predominantly in medium extracranial vessels in patients over 50
- C Polyarteritis nodosa: necrotizing inflammation of medium muscular arteries sparing the aorta and its first-order branches
- D Behcet's disease: neutrophilic vasculitis affecting veins preferentially with venous thrombosis and aphthous ulceration
Explanation
Takayasu arteritis (TA) is a granulomatous large-vessel vasculitis predominantly affecting the aorta and its major branches in patients under 50 years, with strong predilection for Asian women. The pathogenesis involves CD4+ T lymphocytes (Th1 and CD8+ cytotoxic T cells) and NK cells activated by heat-shock protein 65 (HSP65) on vascular smooth muscle cells and potentially via IL-6/IL-17 pathways. These effector cells traffic from the adventitial vasa vasorum inward, mediating granulomatous inflammation at the media-adventitia junction with giant cells, leading to intimal hyperplasia (causing stenosis) and medial destruction (causing aneurysm/dilation). Giant cell arteritis has a similar mechanism but affects people over 50, predominantly involving the superficial temporal artery and ophthalmic artery branches. PAN is a medium-vessel necrotizing vasculitis without granulomas, sparing the aorta.
Reference: Robbins & Cotran Pathologic Basis of Disease, 10th ed.
High-yield for: NEET PGINI-CETNExTFMGEUSMLEPLABMRCP
Written and medically reviewed by the StethoPrep medical team.