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NBME 21 Answers

nbme21/Block 3/Question#12

A 55-year-old man with hypertension comes to the ...

Left renal artery atherosclerosis

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submitted by rocmed(1),

Can't renal cell carcinoma cause invasion of the renal artery, obstructing blood flow (resulting in a bruit), thereby upregulating RAAS and increasing blood pressure?

rocmed  And isn't smoking also a risk factor for RCC? +  
lispectedwumbologist  It is but RCC tends to present later in life (6th or 7th decade). In a 55 year old smoker, atherosclerosis of the renal artery is am much more common cause of bruits +  
seagull  Hypertension is also a risk factor of an atherosclerosis leading to more inflammation. Eventually dilation (aneurysm) might occur... if im wrong then ignore this +1  
seagull  Hypertension is also a risk factor of an atherosclerosis leading to more inflammation. Eventually dilation (aneurysm) might occur... if im wrong then ignore this +  
illogical  Renal Cell Carcinoma has a tendency to invade the Left Renal **Vein** (Pg 134, Pathoma 2018). Thus it has an association w/ obstructed drainage of the Left Spermatic Vein leading to a varicocele. Renal artery stenosis is more commonly due to atherosclerosis (almost 85-90%) or fibromuscular dysplasia. +12  
ratadecalle  With RCC and renal vein invasion you would see B/L lower edema and venous collaterals in the abd wall (Uworld). Also he has a severe headache and confusion which are signs of a hypertensive emergency. +1  

For RCC: (As per UWORLD)

Symmetric bilateral lower extremity pitting edema and tortuous abdominal veins are concerning for an inferior vena cava (IVC) obstruction, which, in the setting of a left-sided flank mass, suggests renal cell carcinoma (RCC) with extension into the IVC.  RCC accounts for >90% of all malignancies arising in the kidney and is highly associated with smoking.  Patients with RCC classically have a triad of flank pain, palpable mass, and hematuria, although many remain asymptomatic until the disease is advanced. RCC is a highly vascular tumor that invades the renal vein in up to 25% of cases.  IVC obstruction can occur due to intraluminal extension and thrombus formation, rather than mass effect from the tumor itself. 

The obstruction can occur acutely or gradually over time.  In chronic cases, collateral venous circulation may develop based on the site of the obstruction.  Prominent abdominal wall collateral veins, as in this patient, suggest obstruction of the upper segment of the IVC.

nor16  high blood pressure, i.e. Hypertension, risk factors for atheroscl., bruit !!! over left abdomen, secondary art. Hypertension. they always want the renal artery stenosis (like vWF in coag. disorders...) +  

Just realized that renal cell carcinoma isn't the correct answer b/c it invaded the venous circulation and not the arterial. BP may not be affected as much. if RCC were the answer then then there would have been edema present and/or renal HTN.

sympathetikey  Also, just thinking out loud, in the case of RCC, it's the kidney tissue that's dysplastic & moving, so technically the renal artery itself isn't dysplastic, right? +  

 +0  upvote downvote
submitted by rainlad(1),

How do we explain the bruit in this case? Also why isn't it left artery aneurysm? That seems like it would better explain the bruit

gdupgrant  The bruit is basically just turbulent flow, which is most commonly caused by artery narrowing. I was just reading https://emedicine.medscape.com/article/463015-clinical on renal artery aneurysm and it looks like most of the hypertension is actually related to a pre aneurysm stenosis, so i think stenosis is the "better" answer, esp. since the pt has like every risk factor for stenosis. To be honest I had not ever really thought about RAA for this case because bruit over RA has been drilled into my head as renal artery stenosis, but i apprecaite seeing how this is a super reasonable answer - just the stenosis is "more likely" +1  

Im not really sure but I think the point is that with the captopril radionuclide scan there is a delay in function of the kidney. What they wanted us to remember here is that when you give a " A pril" to a patient with Renal artery atherosclerosis the renal function worsens because there is constriction of the efferent arteriole

FA 2018 - 567

 +0  upvote downvote
submitted by pg32(7),

NBME/Uworld love to test renal artery stenosis in the setting of hypertensive urgency/emergency. Just because this has been done so many times, you can basically get the right answer from the first half of the question. Pt with end organ issues (headache, confusion) and really high BP (I know it isn't 180/120, but it is really high). So this guy basically has hypertensive emergency. I'm already thinking it's renal artery stenosis. Next sentence? A bruit over the left abdomen. Bingo. Renal artery stenosis, most often caused by atherosclerosis in older men (as compared to fibromuscular dysplasia in younger women).