Fibromuscular Dysplasia

Fibromuscular dysplasia (FMD) is an uncommon medical condition that involves abnormal cell growth in the walls of arteries. Arteries are blood vessels that deliver blood from your heart to tissues in the rest of your body.

FMD can make your blood vessels narrow, bulge or develop a beaded appearance. It may affect:

• Carotid arteries, which are in your neck and connect your heart and brain.
• Renal arteries, which carry blood from your heart to your kidneys.
• Coronary arteries, which supply blood to your heart.
• Mesenteric arteries, which travel to your intestines.
• Other arteries, such as those that travel to your legs, arms or other parts of your body.

Who might get fibromuscular dysplasia?

Anyone can develop FMD. But the condition is much more common in women and people designated female at birth (DFAB) in more than 90% of cases, particularly those aged 40 to 70.

Other conditions may mimic fibromuscular dysplasia, including:

• Ehlers-Danlos syndrome.
• Loeys-Dietz syndrome.
• Neurofibromatosis type 1.
• Williams syndrome.
• Large vessel vasculitis.
• Atherosclerosis.
• Systemic arterial mediolysis.

How common is fibromuscular dysplasia?

Scientists aren’t sure how many people have it because in many people, it doesn’t cause symptoms or it’s discovered incidentally.

What are the types of fibromuscular dysplasia?

There are two types of FMD, based on the appearance of the arteries during diagnostic tests.

• Multifocal FMD is the most common. The arteries look like a string of beads, with a repeating pattern of bulging then narrowing.
• Focal FMD is much less common. It involves narrowed arteries or lesions on the arterial walls. A lesion is an area of abnormal tissue.