55-yo, awaiting transplant, suspect renal neoplasm, next step?

This forum made possible through the generous support of SDN members, donors, and sponsors. Thank you.

DrMetal

To shred or not shred?
Lifetime Donor
15+ Year Member
Joined
Sep 16, 2008
Messages
2,988
Reaction score
2,465
MKSAP 16 question:

55-yo awaiting kidney transplant (ESRD per lupus). Kidney ultrasound reveals a complex-appearing mass suspicious for a renal neoplasm in the right kidney.

Which of the following is the most appropriate imaging study to perform next?

A) CT with contrast (51%) [correct answer]
B) Intravenous pyelography
C) MRI with gadolinium
D) Positron emission tomography (30%) [wrong answer that I chose]

So I understand that CT is the better radiological modality to characterize said mass (really what you might need here is a biopsy, but that wasn't an answer chioce). But really, what's CT going to tell you? That you have a very suspicious mass that looks like cancer. Don't you already have this info from the ultrasound?

In the context of a patient awaiting transplant: isn't the more pertinent conern that of distant mets? That's why I chose PET. If PET is positive in other organs, that might take her off the transplant list. If PET is negative, she can have a nephrectomy and proceed with transplant!

Members don't see this ad.
 
There isn't much a PET will tell you that a CT won't in RCC. Except maybe for bone mets. which are not all that common in the asymptomatic patient with a normal alk phos
 
There isn't much a PET will tell you that a CT won't in RCC. Except maybe for bone mets. which are not all that common in the asymptomatic patient with a normal alk phos
Yeah but RCC can also mets to LNs, liver, lungs too, no? Isn't PET the more sensitive modality for picking that up? Again, this is all in the context of a potential transplant patient. Take away the transplant part of this, and I totally understand doing CT first.
 
Members don't see this ad :)
I have to be honest in that I think this is a stupid question. The "answer" for the workup according to NCCN (https://www.nccn.org/professionals/physician_gls/pdf/kidney.pdf) is:
-CXR
-CT A/P or abdominal MRI
-If clinically indicated: Brain MRI, Bone scan, Chest CT, Needle biopsy
I assume they want to MRI to be wrong because of the contrast. Also, according to our GU oncology professor, RCC often does not show up on PET. Exactly why this is supposed to be general medical knowledge I don't know.
 
  • Like
Reactions: 1 user
I have to be honest in that I think this is a stupid question. The "answer" for the workup according to NCCN (https://www.nccn.org/professionals/physician_gls/pdf/kidney.pdf) is:
-CXR
-CT A/P or abdominal MRI
-If clinically indicated: Brain MRI, Bone scan, Chest CT, Needle biopsy
I assume they want to MRI to be wrong because of the contrast. Also, according to our GU oncology professor, RCC often does not show up on PET. Exactly why this is supposed to be general medical knowledge I don't know.

Yes MR with gad is wrong per contrast (by that same token, wouldnt CT with contrast also be wrong)? Silly mksap.


Sent from my iPhone using SDN mobile
 
MKSAP 16 question:

55-yo awaiting kidney transplant (ESRD per lupus). Kidney ultrasound reveals a complex-appearing mass suspicious for a renal neoplasm in the right kidney.

Which of the following is the most appropriate imaging study to perform next?

A) CT with contrast (51%) [correct answer]
B) Intravenous pyelography
C) MRI with gadolinium
D) Positron emission tomography (30%) [wrong answer that I chose]

So I understand that CT is the better radiological modality to characterize said mass (really what you might need here is a biopsy, but that wasn't an answer chioce). But really, what's CT going to tell you? That you have a very suspicious mass that looks like cancer. Don't you already have this info from the ultrasound?

In the context of a patient awaiting transplant: isn't the more pertinent conern that of distant mets? That's why I chose PET. If PET is positive in other organs, that might take her off the transplant list. If PET is negative, she can have a nephrectomy and proceed with transplant!
A regular old CT has a much better anatomic resolution than a PET. Even a PET/CT typically has much thicker slices than a plain old CT.

Basically, PET as a first step is (pretty much?) never the right answer.
 
  • Like
Reactions: 1 user
Yeah but RCC can also mets to LNs, liver, lungs too, no? Isn't PET the more sensitive modality for picking that up? Again, this is all in the context of a potential transplant patient. Take away the transplant part of this, and I totally understand doing CT first.
PET is generally not sensitive, or specific, for much of anything. We usually use it to confirm what we already suspect/know. And has been mentioned above, RCCs are often not PET avid. I've seen people die from undetected mRCC because somebody decided to do surveillance with PET scans, not CTs.

If s/he is already on HD (you don't mention, but you did say ESRD), a CT with contrast is pretty much no harm/no foul (of course, at that point, so is an MRI w/ gad if they're on Mr. Kidney and the transplant list). But you can get most renal players through a contrast CT with good supportive care. And you can get all the staging information you need with a contrast CT and a good radiologist, as well as operative planning if needed.

Core needle biopsy is still relatively contraindicated in suspected RCC as it is the poster child for biopsy tract seeding and turning a Stage 1 RCC into metastatic disease.

FWIW, I agree that this kind of question is stupid on the IM boards (and borderline stupid on the Oncology boards). But it's par for the course, and at least now you know what you're up against.
 
PET is generally not sensitive, or specific, for much of anything. We usually use it to confirm what we already suspect/know. And has been mentioned above, RCCs are often not PET avid. I've seen people die from undetected mRCC because somebody decided to do surveillance with PET scans, not CTs.

If s/he is already on HD (you don't mention, but you did say ESRD), a CT with contrast is pretty much no harm/no foul (of course, at that point, so is an MRI w/ gad if they're on Mr. Kidney and the transplant list). But you can get most renal players through a contrast CT with good supportive care. And you can get all the staging information you need with a contrast CT and a good radiologist, as well as operative planning if needed.

Core needle biopsy is still relatively contraindicated in suspected RCC as it is the poster child for biopsy tract seeding and turning a Stage 1 RCC into metastatic disease.

FWIW, I agree that this kind of question is stupid on the IM boards (and borderline stupid on the Oncology boards). But it's par for the course, and at least now you know what you're up against.
MRI w/ GAD is explicitly contraindicated for a patient with ESRD on HD. You risk Nephrogenic Systemic Fibrosis in that population (and pretty much only that population, but that's a different story).
 
  • Like
Reactions: 1 user
MRI w/ GAD is explicitly contraindicated for a patient with ESRD on HD. You risk Nephrogenic Systemic Fibrosis in that population (and pretty much only that population, but that's a different story).
This, even though this was mainly an issue with the older gad agents. A CT renal mass protocol will give you the best imaging based characterization of the mass to help figure out the likelihood of malignancy. It will also stage the abdomen for macroscopic dz, renal vein involvement etc. As mentioned above PET is not good for well differentiated malignancy such as most RCC, low grade lung adeno, etc.
 
MRI w/ GAD is explicitly contraindicated for a patient with ESRD on HD. You risk Nephrogenic Systemic Fibrosis in that population (and pretty much only that population, but that's a different story).

I always thought this was an absolute contraindication. Very recently I had an ESRD on HD patient where rheum was insistent on getting an MRI. Rads was cool with this as long as we did HD immediately after getting the gadolinium. We ended up doing the scan, but I couldn't find any EBM to support this practice of NSF "risk reduction" via prompt dialysis. There do seem to be some people recommending it -- just sans evidence.
 
  • Like
Reactions: 1 user
I actually had this exact case in real life and did a lot of research to fight for this woman to get transplanted (it was a liver she needed and she had acute liver failure and we incidentally found this mass). CT can show vascular invasion pretty well which is the number one predictor for RCC met'ing anywhere else. The Israeli database for transplant verified this and we proceeded to transplant w removal of the affected kidney. She did great and hasn't developed any recurrent malignant disease (it's been 6 years).
 
  • Like
Reactions: 1 user
I always thought this was an absolute contraindication. Very recently I had an ESRD on HD patient where rheum was insistent on getting an MRI. Rads was cool with this as long as we did HD immediately after getting the gadolinium. We ended up doing the scan, but I couldn't find any EBM to support this practice of NSF "risk reduction" via prompt dialysis. There do seem to be some people recommending it -- just sans evidence.

I also had a patient in this scenario. Apparently there are a few different kinds of MRI contrast and one of them is less likely to cause nephrogenic systemic fibrosis than the others but I don't remember which one.
 
Top