Fibromuscular dysplasia - renal arteries

Case contributed by Michael P Hartung


Uncontrolled hypertension.

Patient Data

Age: 65
Gender: Female

Extensive beading/undulation of the entire main right renal artery. Probable tiny saccular aneurysm projecting posteriorly from a segmental branch in the interpolar region. Less pronounced, mildly beaded appearance of the main and accessory left renal arteries. No dissection or aneurysm. Possible mild ectasia of the celiac trunk. Normal adrenals.

Case Discussion

Fibromuscular dysplasia as an idiopathic, noninflammatory disease at can affect all layers of small and medium caliber arteries. It most frequently affects the renal, carotid, and vertebral arteries, but can affect any arterial territory.

The "string of beads" sign is most commonly known feature, as is present in this case. Other less common imaging findings include vascular loops, ectasia, arterial dissection, and aneurysm.

Fibromuscular dysplasia in the renal arteries is found in about 1% of hypertensive patients, with strong female prevalence (90%), and mean age of diagnosis of approximately 52 years. It is more common on the right.

In this case, the arterial medial smooth muscle cells are replaced by fibrosis, resulting in a succession of dilatations and multifocal stenoses:  the "string of beads" sign. Unifocal stenosis can also be seen in fibromuscular dysplasia, as a result of focal intimal or subadventitial thickening.

It is appropriate to recommend cervical and intracranial angiography after this examination, as a complication related to disease in the head and neck could result in the most devastating consequences for this patient and would direct more aggressive therapy if indicated.

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