Hi, this is Elliot Fishman, and welcome to part three of our three-part series on patterns of renal cell carcinoma recurrence. We've discussed many different areas, and in part three, we're going to pick up looking at some areas, including bone and muscle. So let's get started.

We left off last time mentioning that you could have metastases to the contralateral kidney, and I was going to show you this case where you look and the patient has adenopathy, there's a pleural effusion, there's para-aortic nodes, and the patient had a left nephrectomy. On the early phase, the right kidney looks pretty good, though there are a lot of nodes in the para-aortic region on the right, and then on the coronal views, you begin to see a mass, relatively hypovascular, in the patient's right kidney. There are nodes present, but again, and some of the nodes are vascular, but this lesion is relatively hypovascular. You can see that on the venous phase, there's a lesion in the upper and lower pole. There are multiple lesions present, which you can see very nicely as you go through the full data set and see it well also on the excretory phase imaging. So this was a patient who had metastasis from a left renal cell carcinoma to nodes, but then also within a couple of years to the contralateral right kidney.

Now the GI tract is involved. Sometimes the patients present with GI bleeding. It's often a surprise finding. If you look at this patient, there's a polypoid lesion that's enhancing. You could think about a glomus tumor, you could think about a GIST tumor, you could think about a carcinoid tumor. You could think about-not a great location-for ectopic pancreas, but you may not have thought about metastatic renal cell carcinoma. That's what that was. The patient had a history of a renal cell. There's a lesion in the left lobe of the liver, but there it is, a polypoid hypervascular lesion. We can see GI bleeding. I've seen cases with multiple gastric lesions. This is a solitary lesion. Just an amazing, amazing case. And here is just a few more images showing you the liver lesion as well as the gastric lesion, which is washing out. So look carefully at the stomach. Again, if they have a GI bleed, you're going to look carefully at the stomach surely, but in every patient, water is a great oral contrast agent. Use it and take a good look at the patient's stomach. And here it is with just some volume rendering, almost making the images look like a virtual colonoscopy.

Now everything I've spoken about or showed you for the most part have been patients with total or partial nephrectomies. Now other patients get partial nephrectomies or ablation, and they may have different complications. Surely you can get local recurrence, particularly if the lesion's not treated well, but with ablation and even surgery, you can get pseudoaneurysms, you can get AV fistulae, and you can get pseudoaneurysms of the patient's renal artery. Here's a patient with a partial left nephrectomy, and you can see on the arterial phase the areas of vascularity. That's an AV fistula in a patient with a partial nephrectomy. You can see it very nicely on arterial phase imaging, but it washes out quickly. You'll see in a moment. Look at the MIP how nicely you see that AV fistula. This patient will need embolization, if not the patient will likely keep bleeding. Here's a patient again, same patient, with that partial nephrectomy, the blood near the patient's kidney, and some of the changes on the later phase imaging. Again, the point making: if you want to see complications like aneurysms and pseudoaneurysms and AV fistulae, you need to do arterial phase imaging to really see it well. On the venous phase you may see it, but it often washes out very quickly. So an AV fistula is a complication of a partial nephrectomy. And here it is again, and you can see just the vessels, and see everything a little bit better on that cinematic rendering. So again, using 3D, a combination of MIP and volume rendering or even better cinematic rendering, will prove to be very, very helpful. And again, adjusting the parameters on the cinematic rendering is especially valuable in this case.

Now here's another patient had a partial nephrectomy, left kidney, and you can see the right kidney and left kidney, and then as you look more carefully at the left kidney, the patient has coming into view right here, is a pseudoaneurysm. There it is, right there. It can be very subtle. That's about a centimeter. Sometimes these pseudoaneurysms will rupture and bleed. Treatment is typically going to be embolization, unless you need to go back in and then you'll resect it. But again, very nicely shown. If you're not careful, you are going to miss these. Again, MIP can show it well, the cinematic here shows it well. But again, the importance on these studies of good injection rates, 4 to 5 cc's a second, 100 to 120 cc's of Omni 350, or Visipaque 320, and again, using that to really show very nicely the patient's pseudoaneurysm.

Another patient, again, active bleed post-partial nephrectomy. You can see the blood in the perinephric space. And of course, when you give IV contrast, the pseudoaneurysm and the site of active bleeding is very nicely shown. So again, when you do partial nephrectomies, when you do ablations, and even when you do biopsy of a tumor, complications do occur and bleeding is one of the common complications, and you need to be aware of that. And here it is again, with MIP imaging showing you the site of pseudoaneurysm in the lower third of the patient's left kidney.

Now what else? We can get bone and muscle mets. Most of the time, bone mets are going to be lytic, rarely blastic. They can have large soft tissue components and be very vascular. Here's a large tumor in the patient's right humerus, really bulky, very vascular, destruction of the bone. And the patient, of course, has extensive nodes also in the anterior mediastinum. Here's that same patient again, the large mediastinal nodes and the large destructive vascular mass involving the patient's humerus. You would have to consider in the differential without a history of metastasis or a primary tumor in the humerus, but once you know the patient has renal cell, you see the nodes, you know what's going on in that patient's left humerus. And you can see it's really a destructive lesion, there's some of the vasculature going to the lesion, there's the 3D of the mass in the anterior mediastinum. So again, bony destruction, large soft tissue mass, mediastinal nodes, most compatible with metastatic renal cell carcinoma in the patient with prior therapy.

Another example. Patient had a left nephrectomy, routine follow-up. The patient had mets to bone at some point, you can see the hardware in place, but look at the patient's left psoas, it's enlarged, and there is a metastasis to the psoas muscle, very nicely shown. Psoas muscle, rectus muscle, gluteal muscles, are all muscles that can be involved in metastatic disease. And again, just like with the other tumors, these lesions are going to be very vascular when the primary is a clear cell. You also look carefully, the transverse process here at L5 is blown out, there's a large destructive tumor there. So when you have bone mets, you need to look really, really carefully because one bone met tends to make certain that you have another one, and then you want to look carefully and make sure you're not missing anything. You want to look carefully at the pelvis, bones that are commonly involved, sacrum, iliac bone, and the femurs bilaterally. Same patient, a little more images. The met to the psoas muscle on the left side, the met to bone, nodal disease by the duodenum, as well as multiple liver metastases. That constant quagmire of not just one lesion, but multiple lesions in multiple organs.

So we've gone through a lot of cases. I've shown you patterns of metastasis. I've discussed protocols, the importance of arterial phase imaging. We talked about rare areas of involvement. I showed you small bowel, I showed you stomach, they can present with GI bleeding. In the stomach, mimic a GIST. In the small bowel, mimic a GIST versus a met versus a carcinoid. We spoke about the varying patterns of metastasis and the importance for the radiologist, for you and me, to not be blindsided by picking up a lesion and being so pleased, we miss three other lesions. Mets are more common in clear cell, and they're vascular, but 85% of renal cells are going to be clear cell in most articles. And arterial phase imaging is therefore critical for picking up and seeing many, if not all of these metastatic lesions. CT will commonly detect tumor recurrence and metastasis before the patient is symptomatic. We started off talking about strategies: the higher the grade tumor, the more frequent you will get imaging. And attention to all body organs and organ systems is critical when you're reading this study for the patient's follow-up to make certain we do not miss any sites of disease that can be treated early. Again, survival at 5 years is over 77% with renal cell, but again, it depends on the staging. Our patients with higher-grade tumors with more aggressive staging will be more likely to recur, and so they especially need to be watched carefully. And with that, I hope you have a great day, and I hope we helped you help the next patient who you're following for renal cell carcinoma. And with that, I wish you a great day.