Fibromuscular dysplasia (FMD) is a rare medical condition. Patients with FMD have abnormal cellular growth in the walls of their medium and large arteries. This can cause the arteries with the abnormal growth to look beaded. The arteries may also become narrow (stenosis).
Most cases of FMD affect the carotid and renal arteries. The carotid arteries are in the neck and connect the heart and the brain. The renal arteries are the blood vessels that carry blood from the aorta to the kidneys.
Fibromuscular dysplasia can also affect the arteries to the intestines (the mesenteric arteries), the arteries to the legs or arms, the coronary arteries (arteries that supply blood to the heart), and arteries in other parts of the body, although this is less common. Many times, arteries in more than one location are affected by FMD.