A 68-year-old woman presented with unstable angina and underwent cardiac catheterization by radial access. There was difficulty advancing the guidewire; a brachial angiogram revealed the following. What is the diagnosis?

Answer D. Fibromuscular dysplasiaThe correct answer is fibromuscular dysplasia. This right brachial angiography has a classic "string of beads" pattern consistent with fibromuscular dysplasia, a noninflammatory, nonatherosclerotic disorder of the blood vessels. Fibromuscular dysplasia is most commonly seen in the carotid and renal arteries but has been observed in nearly every arterial bed.