Fibromuscular dysplasia (FMD) is a non-atherosclerotic, non-inflammatory disease of the blood vessels that causes abnormal growth within the wall of an artery. FMD has been found in nearly every arterial bed in the body although the most common arteries affected are the renal and carotid arteries. There are various types of FMD, with multi-focal fibroplasia being the most common. Further, less common, forms of the disease include focal (previously known as intimal) and adventitial fibroplasia. FMD predominantly affects middle-aged women, but has been found in men and people of all ages. Pediatric cases of FMD are vastly different from that of the adult population, and poorly studied. The prevalence of FMD is not known and, although the disease was initially thought to be rare, some studies have suggested that it may be underdiagnosed. From Wikipedia
