Fibromuscular Dysplasia

Key points

• Fibromuscular dysplasia (FMD) is a non-atherosclerotic, non-inflammatory arterial disease. Renal-artery FMD is an important cause of renovascular hypertension in younger patients; atherosclerosis accounts for >90% of RAS overall.
• FMD predominantly affects women , classically younger or middle-aged women, although men can also be affected. A fixed '90% female' figure should not be treated as universal.
• Renal FMD can present with hypertension and, when severe/bilateral, renal dysfunction. An abrupt creatinine rise after starting an ACE inhibitor/ARB suggests functionally significant bilateral RAS or RAS affecting a solitary functioning kidney and requires urgent assessment.
• Flash pulmonary oedema (Pickering syndrome) is a high-yield presentation of severe renovascular disease, particularly bilateral atherosclerotic RAS or RAS in a solitary functioning kidney.
• MRCP discriminator: young woman + hypertension + renal artery 'string of beads' → fibromuscular dysplasia.
• Do not confuse: FMD is non-atherosclerotic/non-inflammatory; atherosclerotic RAS is typical in older patients with systemic atherosclerosis.