Merck Manual

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Fibromuscular Dysplasia

By

Koon K. Teo

, MBBCh, PhD, McMaster University

Medically Reviewed May 2021 | Modified Sep 2022
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Topic Resources

Fibromuscular dysplasia includes a heterogenous group of nonatherosclerotic, noninflammatory arterial changes, causing some degree of vascular stenosis, occlusion, or aneurysm.

Medial dysplasia, the most common type, is characterized by alternating regions of thick and thin fibromuscular ridges containing collagen along the media. In perimedial dysplasia, extensive collagen deposition occurs in the outer half of the media. Fibromuscular dysplasia may affect the renal arteries (60 to 75%), carotid and intracranial arteries (25 to 30%), intra-abdominal arteries (9%), or external iliac arteries (5%).

Fibromuscular dysplasia is usually asymptomatic regardless of location. Symptoms, when they occur, vary by location:

Ultrasonography may suggest the diagnosis, but definitive diagnosis of fibromuscular dysplasia is made by angiography showing a beaded appearance (in medial or perimedial dysplasia) or a concentric band or long, smooth narrowing (in other forms).

Key Points

  • Fibromuscular dysplasia is most common in women age 40 to 60 years.

  • Patients who have connective tissue disease, who smoke, or who have a family history are at higher risk.

  • Treatment depends on the location and includes angioplasty, bypass surgery, or aneurysm repair.

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