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You can also sign up for a free trial of our premium membership to get access to

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hundreds of case-based micro-learning courses across all key radiology

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subspecialties. Today we are honored to welcome Dr.

0:41

Deborah Baumgarten for a case-based review of renal pathology. Dr.

0:45

Baumgarten completed medical school and all of her radiology training at Emory

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University.

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She was on staff at Emory for over 25 years before moving to Mayo Clinic in

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Jacksonville,

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Florida in 2020 where she specializes in abdominal imaging with a special

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interest in ultrasound and GU imaging. At the end of the lecture,

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please join Dr.

1:04

Baumgarten in a q and a session where she will address questions you may have on

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today's topic.

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Please remember to use the q and a feature to submit your questions so we can

1:12

get to as many before our time is up. With that,

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we're ready to begin today's lecture. Dr. Baumgarten, please take it from here.

1:20

I am thrilled to be here to do a case-based review of renal pathology. Um,

1:24

I encourage you to use the q and a um, also,

1:27

but also I'm gonna have you use the chat feature as well 'cause I'm gonna ask

1:31

you guys some questions and see how you can answer some of these as well.

1:35

So my goals for today

1:39

are that we're gonna get you thinking beyond clear cell renal cell carcinoma.

1:42

When you see a mass, don't automatically knee jerk to renal cell carcinoma,

1:46

especially clear cell variety and also give you some tips on expanding to

1:51

a reasonable differential. So here's our first case.

1:57

Um, it's a 66 year old male who has an elevated prostate specific

2:01

antigen.

2:02

So he was being seen for a prostate M R i but this is the T two

2:07

coronal sort of scout imaging as you will that we would do ahead of time.

2:11

And can anybody tell me which kidney I'm worried about the right or the left.

2:16

If you wanna just type right R or L in your, your chat box. I'll see if,

2:20

if we have a vote here. Okay, great.

2:24

Some people are putting left. Excellent. So as you can see here,

2:27

there's a lesion that's sticking off the bottom of the left kidney,

2:31

clearly not one on the right. So it's incidental.

2:35

The patient then underwent a renal mass protocol workup.

2:41

So we have our non-contrast image,

2:44

we have our arterial phase,

2:47

we have our nephro graphic phase and we have our delayed phase.

2:51

So here's a quick question for you all. Looking at that mass,

2:55

do you think it's true or false?

2:58

Can the enhancement pattern of this lesion help us differentiate

3:03

clear cell renal cell from other tumors such as oncocytoma or other

3:08

forms of renal cell carcinoma such as papillary or chromophobe?

3:12

Do you think that's a true or false statement?

3:14

Go ahead and put T or F or true or false in the chat box.

3:19

Okay, we're all over the place. Good. So some people are saying true,

3:24

some people are saying false and the way I'll answer it is that it's true to a

3:28

point and I'm gonna show you a paper that'll help us sort that out.

3:34

So this is a, a graph,

3:38

a depiction of the enhancement patterns on unenhanced cortico magary neph

3:42

infographic and excretory phases of 298 masses in

3:47

274 patients. And this was published in radiology in 2013.

3:52

And what they found was that clear cell carcinoma,

3:55

which is this top blue line,

3:58

enhanced more than the other subtypes and more than oncocytoma

4:04

and it was accurate.

4:05

This form of enhancement was accurate to differentiate renal cell clear cell

4:10

renal cell from the other masses between 77 and 85% depending upon

4:15

what you were comparing it to.

4:18

Unfortunately the next most avidly enhancing mass is benign and

4:22

oncocytoma, which has a very similar pattern to renal cell carcinoma.

4:27

Although the peak enhancement is a little bit less,

4:29

but you can imagine it's very easy to confuse these two.

4:34

You'll note that chromophobe and papillary renal cell carcinomas enhanced

4:38

in a later fashion generally and again not as much as clear cell

4:44

and oncocytoma.

4:48

So here's an arterial phase and a venous phase on a trauma patient.

4:52

And this was a 19 year old kind of unusual to find a renal mass in

4:57

a 19 year old. But there is a large left renal mass that we can discern here

5:03

already based on the age.

5:04

I mean we're really not thinking about renal cell or at least not clear cell

5:08

renal cell 'cause those are way more common in middle aged men. And again,

5:11

this is a 19 year old incidental with a trauma scan

5:16

but the enhancement pattern is pretty similar to clear cell renal cell

5:20

carcinoma. So given the age and the enhancement pattern,

5:25

this turned out to be an oncocytoma. So again,

5:28

it can be confused for a renal cell but we've gotta use other information as

5:32

well. So

5:36

here's another example of an oncocytoma.

5:38

This was a 75 year old female and she had an incidental mass on a PET scan

5:43

that was performed for other reasons.

5:46

So it follows the expected enhancement pattern of

5:52

a oncocytoma. We have a peak,

5:54

it's 102 in the cortical medullary phase and then it starts fading

5:59

73 and 66.

6:03

But we can't be certain this isn't a renal cell carcinoma.

6:07

So she underwent a biopsy and this was done in 2018 to confirm and it came

6:12

back as an oncocytoma.

6:14

She presented a couple of years later and the mass had grown.

6:17

You can see now it's actually a little bit more exophytic than it had been

6:20

before. Here it's not really deforming, the contour of the kidney,

6:24

it's sticking out a little bit. And again,

6:27

she underwent another biopsy this time though it was done by ultrasound and it

6:31

did again confirm that it was a benign oncocytoma.

6:35

So even benign lesions can grow but she just ended up under,

6:39

ended up going through two biopsies to prove that it was not a renal cell

6:43

carcinoma. Here's another lesion.

6:48

This is a 62 year old man with a very small incidental mass that's in the

6:53

left kidney. You can see it there. There's very little enhancement here.

6:58

So pre contrast it was 30 so it's a little bit hyperdense compared to

7:03

a simple cyst or something. Cortico medullary,

7:06

it was only 43 nephro graphic,

7:09

it was 48 and on the delayed it was 51.

7:12

So it went up just over 20 hounds field units over the course of time.

7:17

So what uh, enhancement pattern do you think this is more typical of?

7:21

What sort of tumor would we be thinking about with this kind of very low and

7:26

then delayed enhancement? Papillary good.

7:29

A couple of people said papillary and indeed this is papillary.

7:33

It's not chromophobe

7:40

but good for, for good measure.

7:42

I thought I would actually show you a chromophobe also.

7:45

So here we have the density at pre contrast is 36.

7:50

Once we give contrast material 118 and this one was

7:55

58 on the more delayed phase.

7:57

So this has a lower peak enhancement but still in this case did enhance and I

8:02

think we'd have a hard time saying this wasn't a clear cell but it did turn out

8:06

to be a chromophobe renal cell carcinoma on resection. All right,

8:11

our next index case is a 68 year old male and he has

8:16

metastatic melanoma as well as a diagnosis of low grade lymphoma.

8:21

And this is a scan of his from May of 2019. Um,

8:26

he does have some sort of high density material in the paracolic gutter here,

8:30

but what I'm more concerned about is this lesion that's sitting adjacent to or

8:35

maybe arising from the kidney. Hard to tell on a single image.

8:40

So I wanna know what you think the best diagnosis is of this and I'm gonna give

8:44

you a multiple choice here. So maybe this is lymphoma,

8:48

we we can have perineal lymphoma, could this be his melanoma,

8:52

could it be a lymphoma or is this some sort of an abscess sort of

8:57

thing?

8:59

So there's really no difference in density as we can really discern on the

9:04

original phase. That's portal phase and on the more delayed phase.

9:08

But before we actually answer the question,

9:10

I've got a couple people saying lymphoma,

9:11

let's just take a look back and forth in time.

9:15

So this is what he looked like in May, 2019.

9:17

This is the index that I showed you.

9:20

There is actually an additional lesion that we can see here,

9:25

but so this is now March of 2019 and we have this lesion here that's growing

9:29

along the um, wall of the uh,

9:32

sort of the lateral abdomen here and maybe there was something we could have

9:37

picked up in that region back in March but it wasn't called at that point and

9:42

now it's gotten a lot bigger.

9:45

You can tell though that the lesion near the kidney looks fairly similar.

9:49

Move forward a couple of months and this lesion is getting much larger.

9:53

So we can tell that this is a very aggressive process,

9:56

whatever it is that's going on. But again,

9:58

the lesion that's near the kidney is relatively stable.

10:03

So this is our index case here again.

10:08

So what do you all think? So now we're saying well lymphoma,

10:10

I've got one vote for lymph angio.

10:14

So this is our pararenal lesion.

10:17

It's relatively low attenuation kind of water.

10:20

This is another patient with another diagnosis.

10:22

This is a diagnosis of lymphoma or perren lymphoma.

10:26

You can see it's more soft tissue attenuation.

10:29

So our answer is that some of you have rightfully said a lymph angio.

10:35

So these are relatively rare benign mesenchymal neoplasms.

10:39

They are neoplastic but not malignant.

10:43

They can look like this be sort of multilocular, they can be unilocular,

10:47

they may be focal, they may be more diffuse, they can be bilateral,

10:51

they can kind of be almost anything. Um,

10:54

I'm excluding an abscess in this case because there's really no enhancement of

10:58

the wall of this thing.

10:59

And there was also no associated inflammation here and there was no uh,

11:04

change in this over time and you'd expect an abscess would've done that.

11:09

Now this is another patient with a much larger perren lymph

11:14

angio you can see here.

11:18

But it looks relatively ocular in these images and it looks relatively,

11:22

you know, very non-aggressive.

11:24

There's just really nothing much going on with it.

11:27

The patient came back less than two weeks later and it looks a little bit

11:30

different.

11:32

The patient also has sudden onset of pain on that side.

11:36

So what do you all think might be going on here?

11:42

Does anybody have a guess? Yeah, someone says infection rupture.

11:47

Okay,

11:48

good you all are thinking along the right terms 'cause we do see that there is

11:52

some uh, inflammatory change or fluid around the kidney too.

11:57

So now we have some enhancing septa.

11:59

We have a perceptible enhancing wall now and again there's some fluid and

12:03

inflammatory change if we look very carefully here next to the kidney versus

12:07

that area. Previously it also looks like it had gotten a little bit bigger.

12:12

So this is now an infected lymph angio.

12:15

So those of you who thought maybe it was infected were correct and this patient

12:18

had it drained and then sclerosis. All right,

12:22

we're gonna move on to the next case here,

12:25

which is a 76 year old male who has a diagnosis of myelo dysplasia.

12:31

So we have a portal venous scan here and we see there's sort of a mixed

12:35

density lesion in the central kidney. Is it in the sinus?

12:41

It's hard to tell.

12:42

It's hard to say whether it's in the collecting system at this point too 'cause

12:45

we don't really define what is the collecting system.

12:49

So what are we gonna do next?

12:53

Somebody says T C C, we wanna know if it's in the collecting system.

12:56

What's the best way for us to now move forward and decide A C T U?

13:01

Okay,

13:02

so if this were an incidental finding and we weren't doing a CT urogram and we

13:07

have technologists that are very uh, attuned to what things look like,

13:12

you may actually end up with a ex an excretory phase just by accident because

13:16

the,

13:17

the texts know that if they see something funny they should just go ahead and

13:21

re-scan it. So here's our case

13:26

at this point. Again, our best diagnosis this could, this could be a lymphoma,

13:31

this could be a urothelial carcinoma. We haven't excluded that yet.

13:36

Extramedullary,

13:37

hematopoiesis an odd thing or could this be an

13:41

angiomyolipoma? So let's rule out one of these right away.

13:46

I'm gonna take all of your advice and I'm gonna do that delayed set.

13:49

So here's my delayed image and we can see clearly that the collecting system is

13:53

running right next to it, but this is not actually within the collecting system.

13:57

This is a slightly different level than this one was the original.

14:00

So we're going to exclude urothelial carcinoma right away. But again,

14:05

before we give the correct answer I wanna go back and forth in time because I

14:09

can. So here's our index time, November of 2016.

14:13

Again that lesion here that looks soft tissue,

14:16

maybe a little lower density tissue here again in the central sinus.

14:21

If we go way back to August, 2005,

14:24

this patient's beginning his care at the hospital a long time.

14:29

We can see that the central sinus really looked normal. Okay?

14:33

And if we go ahead a couple of years we see that the lesion has gotten bigger

14:38

but a little bit less dense. It looks more fatty.

14:42

So it is actually wasn't there a long time ago and then has changed over time

14:47

and actually becomes less aggressive looking.

14:53

So now we've already gotten rid of urothelial carcinoma as a an answer.

14:58

So I see a couple of votes for extramedullary hematopoiesis and I think given

15:03

the history of myelodysplasia,

15:05

I think I might've given it away before we actually went through any of these

15:08

iterations. But here we go. That's what this turned out to be.

15:14

This underlying um,

15:17

this diagnosis is also associated with um,

15:20

other anemias like hemolytic anemia or other hemoglobin neuropathies.

15:25

You can see um,

15:26

extramedullary hematopoiesis in patients that have leukemia lymphoma.

15:31

Um, sometimes even if you have metastatic disease to the skeletal system that

15:36

replaces a lot of the marrow,

15:38

you can also have areas of extramedullary hematopoiesis.

15:42

So it isn't specific to myelodysplasia but this is one pattern of it where you

15:47

get kind of a mixed density soft tissue and,

15:50

and almost a little bit fatty mass.

15:55

So this is an example of a second pattern in another patient who had

15:59

myelodysplasia. She presented um, when she was 85 at um,

16:04

in 2014 and there is this soft tissue that's kind

16:09

of infiltrating around both kidneys and this really

16:14

mimics lymphoma.

16:15

So here are two different patients with lymphoma that looks a lot like our case

16:20

of extramedullary hematopoiesis.

16:23

So lymphoma is also really good to leave in the differential for something that

16:27

looked like our index case or in this case one with a little bit more

16:32

perinephric and tissue and tissue involving the renal sinus.

16:37

We also included angiomyolipoma on the differential just because

16:42

it's again a mixed soft tissue and fatty mass. Um,

16:47

you can usually find the site of origin from the kidney especially when they're

16:50

exophytic 'cause you look for that, you know,

16:52

infamous beak sign and you can tell that this is arising from the kidney.

16:58

You wouldn't have a beak sign with extramedullary hematopoiesis that presented

17:03

with a soft tissue and fatty mass.

17:04

So that might be another differentiator as well.

17:08

We can also have very large angiomyolipoma and I don't think anybody's gonna

17:12

mistake this for anything but an angiomyolipoma.

17:15

It also has a really nice beak sign.

17:20

Alright, let's move on to our next case. She's 72,

17:24

she has anorexia, she has some right upper quadrant pain,

17:27

she's been losing some weight

17:31

and we see a small sort of ill-defined lower pole mass

17:36

or maybe a mass like area in the right kidney.

17:39

And at this point in time this was the only abnormality in the kidney.

17:43

So what do you wanna put in the differential?

17:46

Anybody think of anything that might wanna put? Okay,

17:49

I am getting focal infection or focal pilo got two votes for that renal cell

17:54

carcinoma. Also a good thought.

17:58

So some of the things I'm gonna put in the differential,

18:01

I'm gonna put lymphoma in the differential. I'm gonna put a renal cell,

18:07

I'm gonna put urothelial, I'm gonna put focal pile and nephritis.

18:11

But is this really the order in which I would, you know,

18:14

list these as my differential when I do my report and say hey,

18:19

this is what things could be. I don't think that's,

18:22

this is really the differential. I would put this way.

18:25

The order of likelihood I think I'm gonna put focal pile and nephritis first.

18:29

It is rather ill-defined the patient has been having some

18:34

kind of vague symptoms.

18:35

But again these are symptoms that could also go along with a malignancy.

18:39

So I'm gonna put malignancy second a renal cell before I put urothelial cell

18:44

and I think I'm gonna put lymphoma much lower down. It's um,

18:49

can present as a focal mass but generally has more than one mass and they're

18:53

usually a little more homogeneous than this.

18:55

And I'm gonna give you examples of all of these anyway.

18:57

So this is the order of likelihood I'm gonna put these in.

19:00

Someone else mentioned infarction,

19:02

which I also like in terms of its shape,

19:06

but I would expect to see a little bit less enhancement here unless this is

19:10

actually not enhancement but some hemorrhagic component in which case maybe

19:15

infarct would be a good choice as well.

19:19

So the patient actually underwent a renal mass protocol CT two days later.

19:23

She had the full gamut, she had her non-contrast, her arterial,

19:27

her nephro graphic and her delayed. And this is that same area,

19:30

which as we'd expect didn't change very much over

19:35

a couple of days. However,

19:38

we were able at this point to see a couple of other areas of abnormality in that

19:42

right kidney here. A little bit of uh,

19:45

another little focal area anteriorly and then a little more um,

19:50

rounded area. And this is not the same clearly as the other area.

19:53

So now it's a multifocal process and in the meantime

19:58

she has undergone a urinalysis and

20:03

a urine culture. And what do you think

20:08

it grew? What's the most likely candidate?

20:13

E coli. Exactly. Exactly. And that's what she grew.

20:19

I'm gonna pause here for a second. There's a couple of questions in the, uh,

20:22

question and answer box. So someone asked, I've shown you that we,

20:25

we do a four-phase renal mass protocol here. Is that the recommended protocol?

20:30

It really depends on the indication for what you're doing in the kidney.

20:34

If you are working up a mass at the very least you need a

20:39

non-contrast.

20:40

You need either an arterial or a nephro graphic or even a portal venous phase.

20:46

And then I think a delayed phase is helpful.

20:48

So I think at least three phases are helpful.

20:51

The reason to add the arterial phase would be if you're doing presurgical

20:55

planning and you wanna see the relationship of the renal artery,

20:58

how many renal arteries, that sort of thing. Um, it's helpful for that.

21:03

Um, in where I was before Mayo Clinic at Emory,

21:07

we only did routinely three phases.

21:09

We'd add the fourth arterial phase again depending upon the indication,

21:14

mostly for preoperative planning. Three phases are adequate I think.

21:19

Um, at Mayo Clinic they just prefer to do four phases.

21:21

So I'm kind of going along with the, with the group, um,

21:26

pseudo tumors versus recurrence of renal cell.

21:29

A little out of our realm for this particular case.

21:32

But I'll see if I can get back to that a little bit later. So just remind me.

21:38

Okay, here's that same patient with the multiple areas of abnormality.

21:42

We've got posterior here, a little bit anterior here. So, oh,

21:47

I'm sorry, I got off a little bit. This is another patient, sorry,

21:51

this patient was being screened for cirrhosis and she has again this sort of

21:55

wedge-shaped area here, but also a little bit of abnormality anteriorly.

21:59

And she was as far as we knew, asymptomatic. However,

22:03

when we brought up the possibility that she might have focal pile and nephritis,

22:08

the patient said, well maybe she'd had some fevers at home.

22:13

Um, so they went ahead and did uh, urine cultures and she also grew e coli.

22:17

So this is just another example here of more focal pile and nephritis and again,

22:22

maybe some other subtle abnormality on a more delayed phase here.

22:28

So somebody's asking me about what about IgG four diagnosis?

22:31

That is another possibility. When you see focal renal masses like this,

22:36

I would hope you would also see something wrong in the uh,

22:41

pancreas or perinephric per pancreatic space. Um, you're also not gonna grow,

22:45

clearly not gonna grow e coli on a culture or have an abnormal urinalysis.

22:50

So you have to perhaps think about that in your differential.

22:54

It's not something I trained thinking about.

22:56

It's actually a diagnosis that was described well after I finished my training.

23:02

Um, that I I guess is not top of my brain all the time,

23:05

but is a very good suggestion 'cause that can also present with sort of rounded

23:09

masses.

23:09

The ones I've seen when I've seen it involve the kidney have had more than one

23:13

lesion. Um, but I'm sure there are examples where it's only a single lesion.

23:19

So again, yeah, something else to think about.

23:22

And here's just a more typical case of pyelonephritis to me where we have

23:28

multiple wedge-shaped areas that are involving also the cortex

23:32

of the kidney, not just the medullary regions.

23:35

So you really get blurring of that cortex where here's a little bit more normal

23:39

cortex and then some more cortex that's not quite as normal.

23:45

The other differentiator here is that sometimes with infarction or often with

23:49

infarction you can get preservation of the renal capsular flow.

23:54

So you get that little rim of enhancement around a wedge-shaped area.

23:58

So that can help you differentiate in some cases between infection and

24:02

infarction.

24:05

So this is an example of urothelial carcinoma,

24:08

again presenting on the axial image as a solitary sort of rounded

24:13

area. But when we look at this coronal, you can see that it,

24:17

although it's preserving the renal shape, it's very infiltrative.

24:21

We also have some preservation of that capsule or a little bit of that cortical

24:25

flow here, which again is a bit of a differentiator from infection.

24:34

And again, for completeness sake,

24:35

this is an example of lymphoma where we have multiple very homogeneous

24:40

soft tissue masses involving both kidneys in this case.

24:43

A little asymmetrically on the right greater than the left. So again,

24:48

more homogeneous and and multiple is another pattern of lymphoma.

24:56

Okay, moving along to our case five,

25:00

we have another female and she was being scanned for abdominal discomfort. So

25:07

I'll just let you look at this for a second and then I'll point out that there's

25:11

this rather large mass like area or mass in the

25:16

mid kidney here and you can see it here on the washout as well.

25:24

And if we look, it's following the blood pool here.

25:27

So it looks very similar to the aortic enhancement.

25:31

Does anybody have any guesses?

25:33

So somebody says a column of burin 'cause it does kinda look like the kidney to

25:37

some extent. A hemorrhagic cyst lymphoma,

25:40

T C C A hemangioma aneurysm, I like aneurysm.

25:45

Kind of like it. All right,

25:47

the next phase is going to sin s**t.

25:50

So that's why I kind of skipped this lesion to start this uh,

25:53

image to start with. So here's the next image for you all.

26:00

Now what do you all think this is?

26:04

So this was the index area, but now we have all this other

26:10

serpiginous vascularity here. So yes,

26:13

arteriovenous malformation is what this is.

26:19

So it's just something else to think about.

26:22

And when you have a very homogeneously enhancing lesion, um,

26:26

whether or not you initially see the other vessels associated with it,

26:30

if it follows the blood pool,

26:32

you have to at least think about a very vascular lesion.

26:37

So now I'm gonna show you this as a, as a companion case.

26:40

And this is a 75 year old who had a diagnosis of a pancreatic mass,

26:45

which you can see here. Now why am I showing you this as a companion case?

26:49

Just hold your horses, we'll get there.

26:54

Has this lesion also had innumerable pulmonary nodules as we can see here,

26:59

just lots and lots of them. So we're already thinking, okay,

27:01

this is metastatic pancreatic cancer potentially and that's what it was presumed

27:06

to be a metastatic neuroendocrine pancreatic cancer.

27:11

But here's the rest of this case.

27:16

So we look at his right kidney and we see a lesion here that is

27:21

again following the blood pool. It looks a lot like the one I just showed you.

27:25

That's sort of a big serpiginous looking thing here.

27:30

But it also has a bit of a mixed sort of cystic solid component posteriorly here

27:35

that's a little bit different. That really didn't look like a vessel.

27:38

So it looked a little bit more complex than perhaps that very clean arterial

27:42

venous malformation.

27:44

So someone's thinking metastatic pancreatic from clear cell renal cell. Okay,

27:49

renal cell with an AV f maybe some thrombus in here. These are all really good,

27:55

really, really good thoughts.

27:56

So what happened next was the patient actually underwent a lung biopsy 'cause

28:00

they figured, well this'll prove where it's coming from.

28:05

And this turned out to be metastatic renal cell carcinoma.

28:10

So this, as several people suggested,

28:14

was metastatic to the lung,

28:16

was metastatic to the pancreas renal cell likes to go to the pancreas and other

28:19

retroperitoneal structures. So you know, if it looks like, uh, a horse,

28:25

it's a horse, if it looks like a zebra sometimes it's still a horse.

28:28

So common things being more common.

28:30

This was a renal cell that went to the pancreas and the lung and

28:35

they can have very large vascular channels within them or even have, you know,

28:40

a, a arterial venous connection.

28:44

So this is another example of something that looks very vascular.

28:48

So in this case though,

28:50

the lesion is very vascular but not enhancing as much as the aorta

28:55

on this very arterial phase. So again,

28:58

a little bit less than the aorta and iliac vessels.

29:00

And then on the more delayed phase,

29:03

it's actually retaining contrast a little bit more than the aorta.

29:07

So it's not washing out as fast.

29:09

Does anybody have a thought about what this vascular lesion might be?

29:15

So it's a little bit slower to enhance but then it hangs onto the contrast

29:20

material. Okay,

29:24

they're thinking you're thinking of angio. Okay,

29:28

I'm not sure I've ever actually diagnosed a hemangioma within the kidney.

29:32

Oh here we go. Someone just mentioned pseudo aneurysm.

29:36

Excellent and an A M L 'cause those can have aneurysms in them as well.

29:41

This did actually turn out to be a pseudo aneurysm.

29:43

The part of the history that I withheld is that the patient had undergone a

29:47

partial nephrectomy. So this was a post-procedure pseudo aneurysm.

29:52

So the contrast may wash in faster but it may not, and then it, it,

29:56

it held onto it in this case. So this patient then had to go on to um,

30:00

angiography and embolization so that hopefully it wouldn't, you know,

30:04

before it would rupture and cause a catastrophe.

30:08

Here's another example of a post-procedure pseudo aneurysm in this case on an

30:11

ultrasound,

30:12

this patient was sent in thinking that he had a recurrent renal cell,

30:17

but this was way too close to his original surgery.

30:20

It was only a matter of a couple months.

30:22

And this lesion looked kind of large but you'll notice it has kind of a thick

30:26

wall here,

30:27

a cystic space centrally which starts to fill in with contrast or,

30:31

or at least color flow on the color flow imaging.

30:33

So this was an additional pseudo aneurysm following a partial nephrectomy.

30:38

This was not a recurrence of renal cell.

30:43

Okay, we're moving right along here. We have case six,

30:46

which is a 74 year old female who had another incidental finding on a ct.

30:52

So I've shown you both kidneys.

30:53

I think you can see that there's a lesion here in the right kidney.

31:00

And if we look at the density measurements on it, it starts out at 37.

31:04

So it's a little bit denser than the adjacent kidney.

31:08

It goes to 65 on the um,

31:11

portal venous phase and on a more delayed or nephro graphic phase, it's 71.

31:19

So this enhancement pattern,

31:23

it's similar to a papillary renal cell carcinoma but I showed you one of those

31:27

already. So somebody has said A M L, what else is that?

31:32

Chromophobe R cc. Okay, I like that answer too. Going back to our first slides,

31:37

if this were an A M L,

31:39

does anybody know the buzzwords that go along with this particular type of A M L

31:46

lipid Poor? Yep. Or fat poor A M L.

31:50

And that's what this was. This was a lipid poor A M L.

31:53

The problem with these lesions though is that you can't always differentiate

31:57

them on CT based on this.

31:58

So some people have looked at multiparametric M R I,

32:02

there are some features that might help you determine that it's a lipid poor A M

32:06

L, but if that's not helpful,

32:10

things that are are is it stable over time?

32:13

So this patient two years later it looks exactly the same and four years later

32:17

looked exactly the same.

32:19

So we were very confident without a biopsy that this is indeed a lipid poor A M

32:23

L. But some patients do go on to biopsy of these lesions and in certain cases it

32:28

may be appropriate to biopsy them to prove that it's a lipid poor A M L.

32:34

Okay, this is a,

32:37

I'm gonna contrast this with this particular patient who's a 39 year old

32:42

and this was a chest CT as you can tell.

32:45

And at the very bottom and not even completely included,

32:49

was this lesion sticking off of the right kidney.

32:53

It's slightly denser than the renal parenchyma.

32:55

So it may be solid or it may be hemorrhagic at this point we really have no

32:59

idea. So the patient underwent an ultrasound

33:03

and the lesion has some echogenic areas. So our first thought might be,

33:08

well could this be an angiomyolipoma or is it just a hemorrhagic

33:13

cyst? So what would be the next thing you do with an ultrasound?

33:17

You've got the patient on the table, what are you gonna do next

33:22

Doppler? Absolutely.

33:24

So we turn on the Doppler and clearly there's flow at least in parts of this

33:28

lesion. So it's solid,

33:32

it's not a complex cyst.

33:34

So this patient actually underwent an M R I for further further evaluation and

33:38

it's pretty heterogeneous on this T two weighted image.

33:42

There was no discernible fat in it.

33:46

There's nothing at least internally that's causing any India ink artifact

33:49

inside. It did have a little bit of enhancement,

33:53

which maybe we can see a little bit better on subtracted imaging.

33:56

And this lesion turned out to be a papillary renal cell carcinoma.

34:01

So although we thought potentially could have been a fat poor A M L,

34:05

this ultimately got resected and was a papillary renal cell.

34:09

So there are all kinds of things that can be incidental.

34:15

All right, moving along to our case number seven,

34:17

we have a 60 year old male and he was undergoing a routine renal ultrasound

34:21

because he had an elevated creatinine

34:25

and now this lesion that I'm showing you is a little bit different than the

34:28

other lesions 'cause it seems to be in the collecting system as we can see

34:33

here,

34:33

there's definitely hydro and I'm gonna show you two cine clipse and

34:38

the arrow is just keeping your attention on that area there,

34:41

showing you where that lesion is.

34:42

You can see the hydro and then this is a transverse kind of going back and forth

34:47

and it's hard to keep the lesion in in the plane but it's

34:52

right there.

34:58

So what would be the next step do you think in this patient's workup?

35:07

C T U. Exactly. So this is the patient CT urogram.

35:11

I'm only showing you the non-contrast and the uh,

35:15

initial nephro graphic phase because this kidney did not excrete even after

35:20

45 minutes so it didn't really help.

35:23

But what we can see is that initial lesion that was in the pole of the kidney.

35:29

But we can also see that there is a soft tissue lesion that's filling the

35:32

ureter. That's probably the source of the bad he um, hydro nephrosis,

35:37

you can see a little bit of thickening here as well.

35:39

So this was multifocal urothelial carcinoma as several of you had suggested.

35:44

It might be.

35:48

I'm getting kind of close to time but I wanna see if I can get through a couple

35:51

of more cases here 'cause this next one is a point that I would really like to

35:54

drive home. So this is a 77 year old female,

35:58

again incidental on CT as so many of our renal lesions are.

36:02

She actually has two lesions,

36:03

one that looks relatively water attenuation and another one which is clearly not

36:08

water attenuation. So what do you wanna do next? Nothing.

36:12

You know she's 77, they look small, they don't look very aggressive.

36:17

Do you wanna do an M R I next?

36:19

Do you wanna do a contrast enhanced ultrasound or something else?

36:24

Ultrasound's a good thought.

36:26

It's probably the least is clearly the least invasive.

36:29

So C E U S might be but I'm gonna tell you there's something else we can do.

36:32

And again this harks back to whether you have technologists that know they

36:36

should go back through things that look funny for you.

36:42

So first thing I'm gonna do is just give you a density measurement and it is

36:45

indeed 48 and this was indeed the other one was indeed fluid attenuation.

36:50

So I'm gonna tell you we're gonna do something else. So here we are at 48

36:55

but our text went through and did a delayed image and it's 47.

37:02

So this did not wash out.

37:06

If it didn't wash out it means it didn't wash in.

37:09

So there's no enhancement in this lesion and this is a pretty good rule of

37:13

thumb. If you wait a couple of minutes and nothing changes,

37:16

you can be pretty sure that it's not a very vascular lesion or not a vascular

37:20

lesion at all. So this is a complex cyst,

37:23

it's either hemorrhagic or proteinaceous.

37:25

And at this point if you were still not sure, hedging your betts a little bit,

37:30

a regular ultrasound would be plenty to show that this was just a hemorrhagic

37:35

cyst or a proteinaceous cyst.

37:39

Let me compare that to this particular case.

37:42

So here we have a lesion that's exophytic, that's 53 hounds field units,

37:47

but again we're deli,

37:48

we're aided by delayed imaging and it's 48 hounds field units.

37:53

Five hounds field unit change is not enough to say that something washed in.

37:58

So in this case,

37:59

again it just shows you that this is a complex cyst but just in case we had

38:03

doubts, this patient had come back almost a year later,

38:07

it was exactly the same so we were correct.

38:09

This is just a hemorrhagic or a proteinaceous cyst.

38:13

On the other hand we see this leash in here

38:18

and it's 112 hounds field units

38:22

on our delayed set it's 82 hounds field units.

38:27

So on delayed imaging this washed out 30 hounds field units.

38:31

So we know it washed in. So we know that this is an enhancing lesion.

38:35

So even without non-contrast images we can be confident that this is a

38:40

vascular lesion and in this case it turned out to be a papillary renal cell.

38:45

Again, not enhancing as much as a clear cell.

38:50

And again, just to prove this point,

38:52

'cause I think it's really important to rely on all of the imaging that we have

38:56

on a patient. We see this little lesion here and granted,

39:00

nobody's gonna think this is not suspicious.

39:03

It's got what it looked like multiple little septations that are probably

39:07

enhancing and it has a density of 103 and here's the

39:11

delayed set.

39:13

It's much more homogeneous at this point but it's 74 hounds field unit

39:17

so we know it washed out and this turned out to be a very small incidental clear

39:22

cell renal cell carcinoma.

39:26

All right and then just as a bonus case, this is I promise the last one,

39:30

what do you all think this is?

39:33

Anybody have any ideas? Okay, X P N.

39:40

Good thought.

39:42

I'm gonna show you this is the same diagnosis in another patient.

39:46

Does this help? Yep. Antho granuloma is excellent.

39:51

So I'm going back to our original case here. In this case though,

39:56

usually they're associated with or often associated with stones.

39:59

In this case it's sort of more segmental because a stone is in the upper pole,

40:02

not in the renal pelvis. In this case this is focal or segmental X G P.

40:08

And in this case it also has involvement of the extra renal tissues which it can

40:12

do, which gives it a more aggressive look than just a plan X G P.

40:18

So this is not malignancy but can be locally aggressive. Alright,

40:23

so I just wanted to show you that every mass and I put some of that in

40:27

quotations 'cause not every mass is even a mass.

40:29

Sometimes they're parts of infection or something else,

40:33

but they're not every all going to be clear cell renal cell carcinoma.

40:37

The characteristics of the abnormality can really help you expand your

40:41

differential including the enhancement pattern which is helpful but not a be all

40:45

end all. Also the location of the lesion and whether it's single or multiple,

40:50

don't forget about delayed images or even old images or images of another

40:55

body part that might include the area of interest. For example,

40:59

if the patient underwent a lumbar spine M R I,

41:02

you might have seen that something was there two years ago and it hasn't really

41:05

changed even though it might look a little funny on the,

41:08

the images you're seeing today, it might've been there two years ago.

41:11

And you know,

41:11

who knows if the person reading the lumbar spine m r I noticed it 'cause it's

41:15

not really in their, in their area of expertise.

41:19

Patient features also help you wanna know how old the patient is,

41:22

although unfortunately I'm seeing younger and younger patients with worse and

41:25

worse disease. So not every young person has a benign diagnosis,

41:30

but it does help. And then the symptoms can also help.

41:33

Does the patient have a fever, does the patient have an elevated white count?

41:36

What does their urine look like?

41:38

Can be very helpful And those are things that are not invasive and things you

41:42

can find out that might help you go toward one kind of a lesion or another.

41:46

So at this point I'm gonna see if I can answer some of these questions.

41:49

Do I believe in twinkling to assess calculus burden in urinary tract and to

41:53

differentiate calculus from milk of calcium?

41:56

Twinkling is an interesting phenomenon.

42:00

I think I see sometimes I see twinkling in the kidneys that I have no correlate

42:04

on a CT to show that it's a calcified or stone. I still,

42:09

we still use it but I,

42:12

I kind of put use it with an asterisk next to it.

42:15

But I also think that sometimes you can see things on ultrasound earlier

42:20

even than on CT and you might pick up a very tiny stone that you're really not

42:23

seeing on a ct. So I, I do, we do use it. Um,

42:29

and I certainly anything that is echogenic that I see in the kidney,

42:32

if I don't see shadowing the texts always turn on twinkling just to see if it

42:36

does twinkle and in which case I'd be a little bit more confident about a stone.

42:40

Gotta be careful about vascular calcifications that are in the hilum of the

42:43

kidney. Those can also cause an issue as well. Can I say again,

42:48

which kind of diseases the renal capsule vascularization enhancement are

42:52

preserved and which is not?

42:53

I mentioned that pyelonephritis to me in my experience tends to go the full

42:58

thickness of the kidney and also kind of obscure whatever capsular enhancement.

43:03

So pyelonephritis again can be all the way through and on a

43:08

cortico medullary phase of a, of a study, if that's all you have,

43:13

sometimes just the lack of that cortical enhancement may be your only clut pilon

43:17

nephritis.

43:18

So in those areas the cortex and the medulla are enhancing almost identically

43:23

and you see sort of um,

43:24

areas that do have cortical enhancement and areas that don't.

43:28

And if you wait a little while you'll get a more classic neph infographic phase.

43:32

Transitional cell carcinoma can obviously infiltrate

43:37

all the way through the kidney but it may not and you might still see a little

43:41

bit of capsular enhancement or cortical enhancement next to it.

43:44

Infarcts generally you still have capsular enhancement.

43:48

Do I have any experience with thrombotic nutcracker syndrome?

43:53

Um, Nutcracker syndrome, yes.

43:55

I'm not sure what you mean by thrombotic nutcracker syndrome. Um,

44:02

the Nutcracker syndrome is when um,

44:05

you have the left renal vein sort of crushed between the S M A

44:09

and the aorta. Um,

44:11

usually we don't consider it significance unless they're all so collaterals in

44:16

the left retroperitoneum. Um, it has to be causing some sort of an,

44:21

uh, a disturbance of renal flow for there to be collaterals and if there's no

44:25

disturbance in renal flow,

44:26

you normally don't get those and then it may not be a significant finding and we

44:29

tend to try to diagnose those with um,

44:32

ultrasound looking for elevated venous velocities and a change

44:37

in size of the renal vein.

44:39

Can heterogeneous enhancement in the cortico medullary phase be a normal

44:42

variant? Oh, I wanna ne I never wanna say never,

44:46

but I have to say that it's not,

44:48

I don't think it would be very frequent that you would get, um,

44:54

a, a heterogeneous cortico medullary phase as normal.

44:57

What is my thought about a combined neph graphic exploratory phase?

44:59

We do that in younger patients when we're doing hematuria workups and also, uh,

45:04

younger renal donors where we give a little bit of contrast initially

45:09

and then we combine it with a either arterial or neph infographic to get another

45:13

idea of what the kidneys look like.

45:14

So I think it's really good in younger patients when we're worried about

45:18

radiation dose. But in older patients where we don't have that same worry,

45:22

we prefer to separate them.

45:25

Am I using a bosniac classification on ultrasound? I am not.

45:29

I am describing things I'm giving differentials. Uh,

45:32

we use a lot of contrast material here in ultrasound that I didn't do in my old

45:36

place. Um, but I think it is more appropriate in CT and ultrasound.

45:40

I know people are trying to work on a bosniac for ultrasound.

45:43

I probably will become more apparent or more popular in time to come.

45:48

Which modalities preferred C two or M r I for a definite diagnosis?

45:52

I think it depends in part on patient's stability and what they can tolerate,

45:57

um, and what the radiologist who's reading it is comfortable with. Um,

46:00

in my practice I don't do a lot of M R I,

46:02

so although I can do M R I I I don't do a very much of it,

46:07

so I'm way more comfortable with ct. Um,

46:10

I think you can see more subtle enhancement on an M R I for certain things and I

46:14

think it's easier in some cases to get subtracted images on M R I,

46:17

although we can get them on ct. So I think, um,

46:22

it depends a lot. I mean if I,

46:23

I would rather have a good CT than a crappy M R I quite frankly,

46:27

or an M R I that has a lot of motion artifact.

46:30

So that answers another question too.

46:31

If somebody asked me if I preferred M R ct,

46:34

I actually prefer ct but like I said,

46:36

predominant presence of milk and calcium cyst is a rare pattern of A P K D pro

46:40

in children.

46:41

Do you feel it is common in adults and are we under diagnosing them on

46:44

ultrasound and doppler? Wow. Um, that is something I,

46:47

I can't say that I've given a whole lot of thought to milk of calcium cysts. Um,

46:52

'cause I don't do any pediatric imaging. Um,

46:55

I'll have to say I don't think we see it a lot in adults or if we do or we're

46:59

under diagnosing it because I don't think I've actually, um,

47:03

made a lot of diagnosis of milk of calcium cysts on ultrasound and doppler in A

47:08

P K D, how common is nutcracker cracker? In my experience,

47:12

not very. Um, I'm probably a little skewed because I'm at a, uh,

47:17

tertiary referral center and we get a lot of patients where we're screening for

47:20

Nutcracker because they have headaches and that seems to be an association that

47:25

the neurologists are now looking at. So I think I see workups for it,

47:29

it more like more often than it probably actually exists. Uh,

47:33

does a m l wash out? Is there any,

47:35

is there anything benign than wash out when we don't have non-contrast? Um,

47:43

AMLs should have wash out. Um,

47:46

I'm not sure if we do it early enough they may not wash out significantly.

47:51

Same with papillary.

47:52

It may be very difficult if it just doesn't quite reach that threshold of like

47:56

20 hounds field units. Um, so you've gotta use your best judgment,

48:01

your best guess. What are the other features of the mass AMLs also have, um,

48:06

are more prone to odd shapes like triangular and angular interfaces

48:11

with the kidney. So that might be helpful also. Um, and I, oh,

48:16

in terms of differentiating a renal sooner tumor versus recurrence of R C C?

48:20

Um, recurrent, if, if somebody thinks they had negative margins on a, on a uh,

48:25

partial nephrectomy, um,

48:29

I don't think you're gonna see a recurrence very quickly. You know,

48:32

not in the first few weeks, probably not in the first few months.

48:36

So I would think I know and, and also with ablations,

48:40

I know we tend to do like a three month follow up and then six months. Um,

48:45

I would say I would probably be not comfortable at three months to definitely

48:49

call a recurrence. I might be more comfortable at six months,

48:52

especially if something looked a little bit more lobular and chunky.

48:56

But um, in terms of differentiating it oof,

49:01

um,

49:03

I think some of that is comes with experience and some of it

49:08

is just seeing if the area you're talking about,

49:11

does it really follow the renal parenchyma on all of your phases or is there

49:15

something a little odd about it that gets your attention?

49:18

And don't be afraid to bring somebody back a little more quickly than you might

49:22

otherwise have if you're not comfortable with what something looks at looks

49:26

like. I think I actually got all of the questions and we are a little over time,

49:31

so thank you for hanging on and um, I will stop there.

49:35

Dr. Baumgarter,

49:36

thank you so much for sharing your lecture with us today and for everyone for

49:40

participating in this awesome case review. We really appreciate it.

49:43

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49:56

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