0:00

So let's move on to our last case.

0:02

So this is a patient who had an enlarging renal mass.

0:06

Let's put it that way.

0:08

And so that will sort of focus your eyes, perhaps,

0:12

on the finding that I want you to help me with.

0:15

So T2-weighted image. I don't believe I have a fat saturated

0:18

image, so this is all I have to give you for T2.

0:22

So you can see this lesion here

0:27

arising from the right kidney, you can see it on the coronal images as well.

0:35

And I'll show it to you, on the T1 in and out of phase image,

0:39

whether it's relevant or not.

0:41

I'm not sure, but just for completion.

0:44

Does it have lipid in it? Does it not have lipid in it?

0:51

And then I'll give you T1 pre and post, I think that's reasonable to give.

0:57

Look at the T1-weighted sequence.

1:00

And look at the post contrast sequence.

1:05

Clearly, it's enhancing.

1:06

So I don't think that's a subtle finding.

1:11

And so,

1:13

as we sort of wrap up our cases today,

1:18

this is the last one I'm going to show.

1:20

And this lesion in the right kidney on the T2s,

1:25

T1s post contrast, this is what it looks like.

1:30

We can jump to the last question of the day.

1:33

What's the best diagnosis here?

1:35

Now, we read this case.

1:38

Out of these options, there may be better other diagnoses

1:40

that we can think of, we could talk about that, if you'd like.

1:43

But out of the diagnosis that I'm presenting to you,

1:47

what is the best diagnosis?

1:50

By the way, the way... you know,

1:51

the way we ended up reading this out

1:52

was that this was an enhancing mass.

1:54

We, I'm not saying that we actually provided

1:57

a specific diagnosis, but knowing what the histology was,

2:00

perhaps we could provide this a more specific diagnosis.

2:04

Leiomyoma. Perfect.

2:05

So I realized, as I put these cases together, that there were two cases,

2:08

a leiomyoma that I sort of bookended today and so that certainly

2:15

well,

2:16

I believe you would have gotten it right, regardless.

2:17

But it helped me gauge whether we can sort of

2:20

take some of the lessons from the first case and provide it in this case.

2:22

So this indeed was a leiomyoma.

2:24

These are, again, uncommon tumors.

2:25

You don't see a lot of these.

2:26

That's why I wanted to show it to you.

2:28

A benign tumor arising from the smooth muscle cells.

2:31

Classically, it arise from sort of the capsule of the kidneys.

2:34

When you see these lesions,

2:35

they sort of arise in the periphery and grow outwards.

2:38

And you know,

2:40

I haven't seen a lot of these cases, but if you look at the autopsy data,

2:42

the data suggests it's seen about 5% of patients.

2:45

So that seems like quite a lot to me, to be honest.

2:47

But I haven't seen a lot of these.

2:48

Maybe one of the few that I've actually seen.

2:50

Often, they're incidental.

2:52

And again, the imaging sequences that can help this perhaps come up with a specific

2:56

diagnosis of the T2s, very homogeneous, hypointense,

3:00

and they have variable enhancement.

3:01

In this case, was a quite brisk enhancement.

3:04

On CT non-contrast,

3:06

they appear quite hyperdense and calcifications are very uncommon.

3:09

You don't quite see these.

3:10

And so if you look at the other options

3:12

that I presented to you, this is not a good look for a clear cell

3:15

renal cell carcinoma.

3:16

Clear cell carcinomas are the most common histology,

3:19

but they're very heterogeneous.

3:20

They never look really this dark.

3:22

They have some degree of heterogeneity within them,

3:24

brighter T2 signal, maybe some necrosis.

3:26

So the enhancement pattern is good.

3:28

They're quite hypervascular, but the T2 signal is not.

3:31

Medullary RCC are seen in sick patients with sickle cell trait.

3:36

I've only seen a handful, and the handful that I've seen,

3:38

they're very infiltrative,

3:39

aggressive masses, looking masses, not as well defined as this,

3:44

often had metastasis at the diagnosis, the time of diagnosis, in liver, in bones.

3:50

And so, this looks like just a very simple exophytic mass arising from the kidney.

3:55

And so, you know, medullary would not be a good look for that.

3:58

And they're very heterogeneous.

3:59

They don't look quite T2 hypointense as this.

4:01

Hemangioma, I want to give another mesenchymal tumor there.

4:05

Very uncommon, but their T2 signal is brighter than

4:08

you would expect over here, not unlike a liver hemangioma.

4:13

And so, out of the options, I think a leiomyoma is probably

4:16

the best option over here.

4:17

One of the...

4:18

you know,

4:19

one option that this could be that I didn't put out there

4:21

that I don't have a good way to exclude,

4:24

is the lipid poor angiomyolipoma.

4:28

So angiomyolipomas, almost all of them will contain fat.

4:31

So that's easy, they contain macroscopic fat.

4:33

You know it's an AML.

4:35

But about 5%, around that, will have a lack of lipid.

4:40

And they're going to be filled with soft

4:41

tissue, essentially in vessels and their T2 signal will look quite similar to muscle.

4:46

So this one looks quite similar.

4:47

You can argue that it's a little bit

4:49

darker, but you know, I think that's in retrospect.

4:52

You know, this looks a little bit similar.

4:53

It does enhance like this.

4:54

And so I think, if I were to put lipid-poor AML

4:57

or anyone in the audience say, 'Hey, could this be a lipid-poor AML?'

5:00

I would say, you know what? That's a very good possibility.

5:02

And out of the options that I presented, leiomyoma is the best

5:05

and that's indeed what this turned out to be.

5:08

That's great. A lot of you got that one right.

5:10

So I'm really happy to see that.

5:11

There's a good question that somebody asked for a DWI for splenosis.

5:14

Sure, you can use DWI for splenosis.

5:16

I mean I think the key thing with splenosis and imaging, is it just has

5:22

to look like the spleen and all the other sequences.

5:25

And so even on the diffusion-weighted sequences,

5:27

if it looks similar to what the spleen looks like,

5:29

then, you know, then you can make that diagnosis of splenosis.

5:32

But, so I think that's not unreasonable to use as well as an imaging sequence.