0:01

When we consider extradural neoplasms, we have to

0:05

consider lesions that are derived from the bones.

0:08

So we've already discussed those lesions that are

0:11

related to the nerves in the nerve sheaths, and also

0:16

the neuroblastoma series in the children.

0:19

So now we have to move to primary bone tumors.

0:22

This is an area of great fear among neuroradiologists

0:27

because we don't say that we are the primary

0:30

bone people in the radiology realm.

0:33

We would probably defer to orthopedic

0:36

radiologists or MSK radiologists.

0:38

So I'm just going to go through a few of the more common

0:41

of the primary bone tumors that can present

0:44

as an extradural spinal mass.

0:47

Of the primary benign bone tumors,

0:50

the most common are going to be the aneurysmal bone

0:53

cysts, which may be associated with or

0:55

independent of giant cell tumors.

0:58

And then we have those that are more specific

1:01

to the spine including chordoma and teratoma.

1:04

Here is a CT scan of a bubbly bone lesion.

1:08

This bubbly bone lesion is affecting the pedicle and

1:12

transverse process of a lumbar spine vertebra, and we see

1:16

that it also displaces the thecal sac to the left side.

1:19

This bubbly bone lesion has multiple compartments within

1:23

it, and we would look for fluid-fluid or hemorrhage fluid

1:26

levels within it, as this ended up being an aneurysmal

1:31

bone cyst. A large expansile bubbly bone lesion, which

1:36

may show fluid hemorrhage levels within it.

1:39

This is a patient who has a lytic lesion of the spinous

1:44

process, extending to the lamina and the transverse

1:47

process of a thoracic vertebra.

1:50

This patient's final diagnosis was a giant cell tumor

1:54

but the findings are relatively nonspecific of a lytic

1:57

lesion in the bone. Could this be a metastasis?

2:01

Absolutely. Could this be a plasmacytoma?

2:04

Absolutely.

2:05

Giant cell tumors are one of those lesions

2:08

that are more on the lytic side.

2:10

This is a patient who has a bubbly bone lesion to the left side.

2:15

And on the MRI scan, we can see that it has heterogeneous

2:20

signal intensity on multiple pulse sequences.

2:22

This is T1-weighted scan and we notice this is somewhat

2:26

bright on the T1-weighted scan before contrast. On the

2:30

STIR image, bubbly lesion with multiple compartments to

2:34

it, extending on the T2-weighted

2:37

scan into the transverse process,

2:39

the pedicle, and out into the extra spinous location.

2:44

And with gadolinium enhancement with fat suppression, we

2:48

see that there are areas that are

2:50

bright on signal intensity.

2:52

Now, we'd have to look pre-gad to post-gad and determine

2:55

whether there is actually any enhancement or not.

2:58

What we can see is a little bit

3:00

of a meniscus here of fluid, and this did turn out to be

3:04

an aneurysmal bone cyst with associated giant

3:07

cell tumor. So they may occur in concert.

3:10

This is another aneurysmal bone cyst.

3:12

It didn't really show fluid levels but it was located in

3:16

the posterior elements and was compressing

3:18

the spinal cord from posteriorly.

3:21

You note that at the cervicomedullary junction, there

3:23

is very faint high signal intensity

3:25

on the T2-weighted scan.

3:26

We note that it's an extradural lesion because there's

3:31

narrowing of the thecal sac adjacent to the big mass.

3:34

And we see the relative high signal intensity focally at

3:39

the C1-C2 level where the cord is

3:44

being compressed and is edematous.

3:46

The bright signal intensity on the T1-weighted scan may

3:49

suggest the diagnosis of aneurysmal bone cyst, but the

3:53

classic appearances with fluid hemorrhage levels.

3:57

This is more in keeping with the sweet

4:00

spot for neuroradiologists.

4:02

Chordomas are tumors that affect the sacrococcygeal

4:07

region and the clivus, a lot more commonly

4:10

than the cervical spine.

4:11

However, they can occur in the cervical spine associated

4:16

with either the intervertebral

4:18

disc or the vertebral body.

4:19

In this situation, we have a patient

4:21

who has a T2-weighted scan,

4:23

post-gadolinium fat-suppressed

4:25

T1-weighted scan and a CT scan.

4:28

We see that this lesion is located predominantly

4:32

anterior to the spinal canal.

4:34

However, there does appear to be an area where

4:36

it communicates with the vertebral body.

4:38

This is an important distinction because it goes from a

4:41

vertebral body lesion to a paraspinal or pre-

4:44

vertebral or retropharyngeal lesion.

4:46

The communication with the vertebral body was relatively

4:50

focal on the CT scan, with the lesion located

4:54

in a left paracentral location.

4:57

Chordomas are characterized by being very bright in

5:00

signal intensity on T2-weighted scan, and showing somewhat

5:03

heterogeneous contrast enhancement. In the clivus,

5:07

they are the most common lesion.

5:09

In the sacrum, they are very common,

5:12

probably the most common lesion in the adult.

5:14

In children, we would consider a teratoma and we also

5:18

would have to consider metastatic

5:20

disease in the older adult.

5:22

Here is a vertebral body lesion in the cervical spine

5:26

that has bright signal intensity on T2, dark signal

5:30

intensity, as you see on the center image on T1,

5:33

and was slightly hyperdense on the CT scan.

5:38

Biopsy proved a chordoma.

5:40

This is unusual because we usually think of chordomas

5:43

more likely at the C1-C2 level or extending

5:46

into the intravertebral disc.

5:47

But this was an isolated C6 vertebral body chordoma.

5:52

Here is a classic lesion which shows a

5:56

bullseye effect, with a lytic lesion,

6:00

with a central area of hyperdensity on the CT scan.

6:05

This would be classic for an osteoid osteoma.

6:08

If the patient had pain at night that was

6:11

relieved by aspirin in that spinal area,

6:15

it would have read the textbook on osteoid osteoma.

6:19

Osteoid osteomas are related to osteoblastomas.

6:23

We say when there are... when the osteoid osteoma grows,

6:26

maybe even greater than two centimeters,

6:29

we're more likely to call it an osteoblastoma.

6:32

When we have osteoblastomas,

6:33

you may see them in association with an aneurysmal

6:37

bone cyst, very similar to giant cell tumors.

6:41

This was a spinal osteoblastoma compressing the spinal

6:44

cord in the upper to mid thoracic region.

6:47

And it looks like any other bone tumor from

6:51

the standpoint of being dark on T1,

6:54

somewhat bright on T2, and showing contrast

6:57

enhancement on MRI. As I mentioned,

6:59

osteoblastomas are larger than osteoid osteomas.

7:03

It may have the same vascularitis and can be

7:05

obliterated by obliterating the vascularitis.

7:10

When they occur in the spine,

7:11

they're more common in the lumbar region and in the

7:14

posterior elements than anteriorly

7:16

in the vertebral body.