The non-atherosclerotic disease with a 'string of beads' appearance most commonly affecting renal or carotid arteries is?

• A. Atherosclerosis
• B. Vasculitis
• C. Fibromuscular dysplasia
• D. Thrombosis

Answer: (C)

The beaded, alternating narrowing and dilation pattern seen on angiography points to fibromuscular dysplasia, a non-atherosclerotic disease of medium-sized arteries. It causes segments of stenosis interspersed with aneurysmal dilatations, most classically in the renal and carotid arteries, which gives the characteristic string-of-beads appearance. This condition typically affects younger to middle-aged women and can present with hypertension when the renal arteries are involved or with transient neurological symptoms when the carotids are affected. This pattern helps distinguish it from atherosclerosis, which involves plaque buildup and calcifications in older individuals, from vasculitis, which is inflammatory, and from thrombosis, which tends to cause occlusion rather than a segmented beading appearance.