0:01

Here is another case of chondroblastoma,

0:04

slightly differently, uh, presented,

0:06

but at a similar location.

0:08

For here, I'm going to show you plain films,

0:11

CT scan, and MRI, so you get an idea that this

0:15

really is a cartilage-based type of tumor, which

0:19

is sort of hard to appreciate simply on MRI.

0:23

Here's the plain radiograph.

0:24

We have two images.

0:26

They're very similar projections.

0:27

But basically what I want to show you is

0:30

you've got this relatively well-defined cystic

0:33

sclerotic lesion involving, looks like part

0:36

of the epiphysis, part of the metaphysis.

0:39

And if you look very carefully, you actually

0:41

even have a little bit of periosteal reaction.

0:43

Okay?

0:43

So don't let that bother you.

0:45

You can have periosteal reactions

0:48

in benign lesions, especially if

0:50

it's been injured in some way.

0:52

So don't let that bother you.

0:54

Persuade you into going to

0:55

something more malignant.

0:57

Again, same thing like we talked last time.

0:59

It's centered in the epiphysis,

1:01

extends to the metaphysis.

1:03

One difference is the growth plate isn't fused.

1:05

So here, I may consider giant cell tumor

1:09

slightly higher on the differential diagnosis,

1:11

but I'm going to discount that because

1:13

of the way it appears in the lucent area.

1:15

There are these little lines, the

1:17

serpiginous lines, and you can actually

1:18

see those lines a little bit better on CT.

1:21

The little arcs and whorls which

1:23

are the hallmark of cartilaginous

1:27

ossification or calcification.

1:29

Okay, that's what you're looking for.

1:31

Don't let the fact that you have a

1:32

growth plate that's fused persuade you

1:35

into calling this a giant cell tumor.

1:38

There may be an effusion, hard to tell.

1:40

We'll have to look at the MR for that.

1:41

So now I'm going to switch over to the CT scan.

1:45

We've got a coronal reconstruction

1:47

here of that CT scan.

1:48

This basically is a much more detailed

1:51

image, if you will, of your plain

1:52

radiograph that you just looked at.

1:54

And this is the axial around the same level.

1:57

So remember I mentioned the arcs

1:59

and whorls of the calcification?

2:02

Let me get back to the CT right side here.

2:06

And this is what I'm talking about.

2:08

Right here.

2:09

See these little areas of matrix that sort of

2:11

look like bone marrow that you see elsewhere?

2:15

That's cartilaginous calcification.

2:17

Dark stuff is cartilage.

2:19

And the bright stuff is the cartilage

2:21

that's actually becoming ossified.

2:22

That's why it's called a chondroblastoma,

2:24

because it's a cartilage-based tumor.

2:26

Very, very well-defined, mature periosteal

2:29

reaction that we saw in the plain radiograph.

2:31

Yes, the growth plate is fused, but don't let

2:34

that bother you, because you've got what looks

2:36

like chondroid matrix in the epiphysis, right?

2:41

And so, if that's the case, the majority of these

2:44

lesions, in fact, the vast majority of these

2:46

lesions are going to be chondroblastoma.

2:47

Benign chondroblastoma.

2:49

Now, let's see what the MR looks like.

2:51

Going back here, I'm going to bring down

2:56

our coronal fluid-sensitive

2:59

fat-suppress sequence.

3:00

I'm going to zoom in just a little

3:02

bit so you see what's going on.

3:04

Make it a little darker.

3:05

Okay, so here is our lesion.

3:08

Again, you get the hint that there's some

3:11

arcs and whorls, some complex architecture,

3:15

if you will, within this well-defined mass.

3:18

Centered in the epiphysis.

3:20

Extends to the metaphysis.

3:22

Eccentric in its location.

3:24

Not centered.

3:24

Eccentric.

3:26

Abuts the articular surface,

3:27

but does not penetrate it.

3:29

In this particular case, we

3:30

do have a joint effusion.

3:32

Presence or absence should not

3:33

dissuade you from a chondroblastoma.

3:36

And what else?

3:37

Edema.

3:38

Look at all this edema that

3:39

you have around this lesion.

3:41

You should have edema around

3:43

a chondroblastoma lesion.

3:46

So this is benign, and it may need to get fixed.

3:50

You know, they may have to go in there

3:51

and curettage it out, prevent pathological

3:53

fractures, but this is not malignant.

3:56

It probably won't come back once it's fixed.