The ‘String of beads’ or sausage appearance of the renal aery is due to
**Core Concept**
The "string of beads" or "sausage" appearance of the renal artery is a radiological finding associated with fibromuscular dysplasia (FMD), a non-atherosclerotic, non-inflammatory vascular disease. This condition primarily affects the medium and large arteries, particularly the renal and carotid arteries.
**Why the Correct Answer is Right**
Fibromuscular dysplasia leads to the formation of stenotic and aneurysmal lesions in the affected arteries. These lesions give rise to a characteristic "string of beads" or "sausage" appearance on imaging studies, including angiography and CT angiography. The lesions are typically composed of fibrotic and muscular elements, which cause the artery to appear beaded or sausage-like. This appearance is a result of the alternating segments of stenosis and dilatation along the length of the artery.
**Why Each Wrong Option is Incorrect**
* **Option A:** This option is incorrect because FMD is not caused by atherosclerosis, which is a different type of vascular disease.
* **Option B:** This option is incorrect because vasculitis is an inflammatory condition that affects the blood vessels, whereas FMD is a non-inflammatory condition.
* **Option C:** This option is incorrect because hypertension is a consequence of FMD, not its cause.
**Clinical Pearl / High-Yield Fact**
Fibromuscular dysplasia is a common cause of renovascular hypertension in young women. It is essential to consider FMD in the differential diagnosis of hypertension, especially in patients with a family history of the condition.
**Correct Answer: C. Fibromuscular dysplasia.**