<prompt> Renal aery stenosis may occur in all of the following, except :AtherosclerosisFibromuscular dysplasiaTakayasus aeritisPolyaeritis nodosa  <response>: Answer is D Polyaeritis nodosa Amongst the options provided renal aery stenosis is least likely to be seen in association with Polyaeritis nodosa. Atherosclerosis and Fibromuscular disease - Renal aery stenosis is produced predominantly by atherosclerotic occlusive disease 80 to 90 of patients or tibromuscular dysplasia 10-15 of patients.- CMDT06 p 460 - he common cause of renal aery stenosis in the middle aged and elderly is an atheromatous plaque at origin of renal aery. Harrison - In younger women stenosis is due to intrinsic structural abnormalities of the aerial wall caused by a heterogenous group of lesions called fibromuscular dysplasia. - Harrison 16 1707 PAN or Takayasu aeritis ? CMDT do not mention PAN or Takayasu aeritis as a cause for renal aery stenosis. However, Takayasu aeritis is ceainly a more common cause of renal aery stenosis than PAN. Takayasu aeritis Aoo-aeritis is beleiveds to be the most common of renovascular hypeension in India and China. - Diseases of Kidney and Urinary Tract 8th1279 A number of research publications, however show Takayasu aeritis as a cause for renal aery stenosis. PAN Although renal involvement is seen in upto 60 of patients with PAN its pathology does not involve renal aery stenosis. The pathology involves aeritis without glomerulonephritis and is characterised by aneurysms of small and medium sized aeries. Stenosis of main renal aery is an unusual association. Causes of Renal aery stenosis : Atherosclerosis Fibromuscular dysplasia Non specific Aoo aeritis Takayasu aeritis and giant cell aeritis Takayasu Giant cell Antiphospholipid syndrome Transplant renal aery stenosis Renal aery embolism Dissecting aneurysm of aoa Radiation aeritis 