0:00

Moving on to our next case. So young female, 12 years old.

0:06

So remember here, the physes are still open.

0:12

And here we have the MR images. We have a lesion here. And

0:19

can we have the question, please? What will be the treatment of choice

0:23

in this case? Will it be antibiotics? Will it be chemotherapy?

0:28

Will it be curettage and bone grafting or will it be radiation?

0:34

Let's look at the answers. Oh, majority said antibiotics because for an

0:40

epiphyseal lesion, an important differential is infection. But the correct

0:44

answer here is chondroblastoma, and that's exactly the reason why I've included

0:48

this case. Let's review what are the imaging features of chondroblastoma.

0:54

These are benign cellular cartilage tumors. They are located in the epiphysis

0:59

of the long bones of the extremities. They occur almost exclusively in patients

1:04

under 30 years of age. And again, I have Dr. Helms's dictum here.

1:09

The differential diagnosis of the lytic lesion and the epiphysis of a patient

1:13

under 30 years of age is short and simple, infection, chondroblastoma, GCT.

1:19

So, GCT is easy to exclude because it'll usually seen after 30 years,

1:23

after closure of physes. The real two differentials are infection and chondroblastoma.

1:30

They do look different. This is more like a well circumscribed lesion, which

1:33

is often T2 dark, intermediate to T2 dark. The only reason why

1:41

it gets confused with infection is because this chondroblastoma is known

1:45

to incite a lot of surrounding bone marrow and soft tissue edema.

1:49

But infection looks different. It'll have a thick T2 hyperintense rim, which

1:54

will have T1 corresponding T1 hyperintensity. The inner margins of infection,

2:00

like if it's an intraosseous abscess, the inner margins will be very irregular

2:04

and the center part never enhances because it's a liquefied pus in the

2:09

center of the abscess, and it'll show very strong central restrictive diffusion.

2:14

Whereas, chondroblastomas will show uniform enhancement or at least patchy

2:17

enhancement and will not be centrally completely necrotic. Imaging features,

2:23

these are sharply marginated predominantly the lytic lesions in the epiphysis.

2:27

They're usually centric, so it's like how it is centrically located.

2:31

They will often have a thin sclerotic rim. And if large,

2:35

these lesions can extend into the metaphysis. Though the growth plate is

2:39

open, they can transgress, and they can extend from epiphysis to the metaphysis.

2:45

Calcification, though it's a cartilage tumor, chondroblastoma, matrix calcification

2:50

is seen only in 25%40% of the cases. Then again,

2:54

when you see such a well circumscribed lesion, which

2:57

it's not fluid, bright like an abscess, and it does incite marrow edema,

3:02

but not to the extent how it might have been an infection.

3:06

Now, consideration when you're thinking of a tumor, you're thinking of giant

3:09

cell tumor, but as I said, this will probably after fusion of physis after

3:12

30 years of age. Primary ABC will show blood fluid levels and clear

3:17

cell chondrosarcoma is also a good differential for an epiphyseal cartilage

3:20

lesion, but again, seen in older patients after closure of physis. Classic

3:28

MR imaging feature for this lesion is they incite a lot of surrounding bone

3:34

and soft tissue edema. There's certain benign bone tumors

3:37

that are known to do this. And the common ones are osteoid osteoma, osteoblastoma,

3:41

and chondroblastoma. So, whenever you see so much of edema in a young

3:47

patient, and there is a central focal abnormality, think of some of the

3:51

benign bone tumors that can do that, and this will be one of

3:55

the differentials of the lesion is in the epiphysis, and sometimes chondroblastoma

3:59

have secondary ABC formation, so they'll show fluid levels. Treatment will

4:04

be, again, curettage excision, and they can use a high speed burr to

4:08

reduce the chances of recurrence. And occasionally, they will require a

4:16

wider resection once they have a local recurrence, because there has already

4:21

been a resection. To strengthen the bone after second surgery, they will

4:26

require a wider excision and allograft placement. Okay.

4:33

Another companion case here. Another larger lytic lesion is centrically

4:40

located in the epiphysis reaching the subchondral bone. Obviously, the differential

4:45

that we are considering here is a giant cell tumor, but is this a giant

4:48

cell tumor? The patient is only 13 years, that's the age here.

4:52

This is too young for a giant cell tumor. It's often,

4:54

as I said, is seen after 30 years of age, though the physes are fused in

4:59

this patient, but it's still very young for GCT. And this was the

5:05

MR imaging appearance. You can see a whole lot of surrounding edema that's

5:09

showing enhancement. This usually doesn't happen with GCT. So, GCT is typically

5:14

don't incite a whole lot of marrow edema around there. This was another

5:18

case of a big chondroblastoma, which mimic a giant cell tumor on plain radiographs.

5:24

But then if you put the age and associated imaging features like edema enhancement

5:29

on MR, you can render a specific diagnosis.

5:33

Okay. So, chondroblastoma, the things that you need to remember is a lytic

5:37

lesion in the epiphysis in patients less than 30 years of age,

5:41

particularly when the physes are open. And on MR, you'll see intense surrounding

5:45

bone and soft tissue edema. These are your things that will help you clinch

5:49

the diagnosis.