0:01

Okay. So we gonna move on to case number 2. We have a

0:04

49 year old man with diplopia and headaches.

0:08

And I'm gonna go to that case. Okay, and here... Actually,

0:15

I'm gonna start with CT. So on CT,

0:18

you can see there's this large, very lytic mass centered in the clivus,

0:24

a little bit eccentric to the right. It's got very destructive changes.

0:29

There's soft tissue kind of extending into the adjacent sphenoid sinus as

0:33

well. It extends back through the dorsal aspect of the clivus, so probably

0:38

some intracranial extension. It rose into the carotid canals, really bilaterally

0:44

along the Petri segment and cavernous segments. And then also even extends

0:50

into the superior aspect of the nasopharynx and along the foramen lacerum

0:55

on the left. So fairly large tumor, very aggressive bony changes,

1:01

lots of erosion on CT. So, of course, you start with this on a head CT,

1:06

you're obviously gonna recommend an MRI to further characterize the skull

1:09

based lesion. And here on the T2 weighted images, you can see this

1:15

very, very T2 hyperintense lesion. Again, almost as bright as CSF,

1:20

but it's centered more in the midline. It does extend vulgile into the

1:25

prepontine cistern, fairly large tumor, sort of wraps around the carotid

1:30

bilaterally, more so on the right, and extends into the prepontine cistern

1:36

and causes a mass effect on the brainstem as well.

1:41

Very bright on T2, but on CT or on post contrast images,

1:44

just some variable, little bit of patchy enhancement. It's certainly enhancing,

1:49

but not really avidly enhancing, just sort of patchy enhancement by some

1:53

of its relatively hypo enhancing, but certainly involving those carotid

1:59

arteries. And then this is just a CT of sagittal image,

2:04

just again showing just how large this lesion is, centered in the clivus,

2:09

a little bit of bulging into the superior nasopharynx. But really,

2:12

if you put sort of the center of this lesion, it really is

2:14

in the clivus with fairly good amounts extending into that prepontine cistern.

2:20

Okay, going back to our PowerPoint. So again, salient imaging findings,

2:29

destructive, aggressive clivus mass extending into the adjacent carotid

2:34

canals. On the sagittal T1 weighted image, which I didn't show you,

2:38

but you can see there's replacement of the normal marrow within the clivus,

2:44

extending into the sphenoid sinus. And you can maybe appreciate that the

2:48

pituitary gland is actually separate from this lesion. The infundibulum

2:51

and pituitary gland is pushed up, but it's actually separate from this lesion.

2:56

And again, on the T2 weighted images that we showed, it's very,

2:59

very T2 hyperintense, almost as bright as CSL. Gosh, I keep doing that.

3:05

And then this is just to compare. Remember, always look on your sagittal

3:08

T1 weighted images. Look at your clivus on the sag T1. You can

3:12

see this fatty marrow, normal T1 hyperintense marrow on the clivus. So you

3:16

wanna make sure that that is not replaced in older patient.

3:24

And then here's your pituitary gland. So here's the poll question for this

3:28

case. What is the correct diagnosis? Is this metastasis, lymphoma, pituitary

3:37

macroadenoma, chordoma, or chondrosarcoma? And you guys have probably had

3:42

enough time. Let's show the answer. Okay, very good. Chordoma. Yes,

3:52

this is a... Again, I'm starting out easy. Hopefully I'll get a little

3:56

bit harder, but this is a fairly characteristic example of chordoma. We

3:59

sort of alluded to it in the last case.

4:02

So clival chordomas, again, are a very locally aggressive tumor. They arise

4:07

from the cranial end of the... Well, this clival chordomas arises from the

4:11

cranial end of the nodal chordoma. But remember, you can have chordomas

4:14

that occur all the way along the primitive notochord, from the skull base

4:20

all the way down to the sacrum. Older patients typically are more associated

4:23

with the sacral chordomas, and then you can have them along the cervical

4:27

spine and elsewhere along the spinal canal as well. But at least a

4:30

third of them present in the clivus and the skull base.

4:32

And these are usually in the younger patients, average age 20 to 40, say

4:37

20 to 50 for presentation for these clival chordomas. Patients can present

4:42

with double vision diplopia, often related to dorello's cranialis right

4:47

here, which extends through and into dorello's canal, as well as headache

4:52

and other cardiomyopathies, and the treatment is surgical resection or radiation.

4:57

So again, just to summarize the things that we talked about,

5:00

midline, expansile, well circumscribed mass, variable enhancement. Some

5:05

of these can very avidly enhance, and some can just have

5:08

very minimal enhancement, so called non enhancing or minimally enhancing

5:13

chordomas. But it is important to see at least some enhancement to differentiate

5:18

from the benign equidosis phislifera. I have trouble with that one.

5:25

Say that 10 times fast. But the equidosis lesions are also notochordal remnants

5:29

that are benign and can occur along that dorsal aspect of the clivus, very

5:34

T2 hyper intense, but typically have zero enhancement and are asymptomatic

5:38

and usually pretty small. So once you start getting bigger lesions, you

5:42

really want to worry about chordoma, even if there's not a ton of

5:45

enhancement. Again, MR findings, again, classically very, very T2 hyper

5:52

intense, intermediate to low signal on T1, and we talked about the enhancement.

5:57

You want to make sure you discuss in your dictation its relationship to

6:01

the carotids, optic nerves, cavernous sinus, and even those ones that extend

6:05

significantly in the prepontyl system. You want to talk about the protibubasal

6:08

involvement as well. The differential, of course, includes the skull based

6:13

chondrosarcoma. Again, we talked about this a little bit. It's a lytic mass

6:18

centered at the pitroclival synchondrosis, sort of more eccentric than a

6:22

clival chordoma. Typical chordomas are more midline. These are more off

6:26

center. Again, 50% of these can have chondroid matrix, those arcs and rings.

6:31

If you have a more destructive lesion in general,

6:36

you want to favor chordoma. Remember, skull based chondrosarcs typically

6:39

have more of a narrow zone of transition and are well marginated, as

6:44

opposed to clival chordomas are usually a little bit more destructive.

6:50

Again, these are very hyper intense on TT with heterogeneous enhancement,

6:53

and you want to look at the carotids on all of these cases,

6:57

of course. Another differential for kind of an aggressive appearing clival

7:03

mass is an invasive pituitary macroadenoma. Often, we think of macroadenomas

7:08

sort of extending up into the supercellular cistern, but remember, invasive

7:12

pituitary macroadenomas can also extend inferiorly into the clivus and skull

7:16

base and present with a lytic clival mass. The key to making this

7:20

diagnosis is to see that the pituitary gland is, even on the T1, you

7:24

can see it's a little bit different in signal. Sorry, it's actually,

7:28

there's not much separation from the pituitary gland, and on the post contrast

7:33

images, it's sort of encased and involved with this tumor.

7:37

So you want to make sure, if the pituitary gland is indistinguishable from

7:42

the lesion, then you want to suggest more of a pituitary macroadenoma, as

7:46

in this case, and you can see the tumor was extending into the

7:49

cavernous sinus on the right. Also remember that macroadenomas are going

7:54

to be relatively T2 hypo intense. The other two lesions we showed already,

7:58

chordoma, chondrosarcoma, are going to be very bright on T2. If you have

8:03

a dark lesion on T2, a lytic clival mass

8:07

that's dark on T2, do not put chordoma or chondrosarcoma in your differential.

8:11

That's not what it's going to be. And then finally, when you're looking

8:15

at lytic aggressive skull base mass, you should always consider the possibility.

8:20

Remember I used to say in training, they used to tell me METS, myeloma,

8:23

lymphoma. Should say those kind of at the same time when you're thinking

8:27

about an aggressive skull base mass, because they can all look pretty similar

8:31

on CTE and MRI with an aggressive destructive lesion and a trans spatial

8:36

infiltrative tumor that's relatively hypo intense on T2 weighted images

8:43

due to hypercellularity. It's actually really lymphoma is obvious, often

8:47

really hypo intense on T2 as our plasma cytomas and often

8:55

metastasis depending on the tumor type. And because it's really hypercellular,

9:00

often lymphoma has this relative hypo enhancement pattern.

9:05

And you can often see some soft tissue in the nasopharynx in these

9:09

cases. Always look for a separate pituitary gland. This pituitary gland

9:13

was pushed up. And so this ended up being a case of lymphoma. And

9:17

this is the patient's nasopharynx. So again, look for sort of lymphoid tissue

9:21

hypertrophy and enlargement of the adenoids in the nasopharynx to suggest

9:27

a lymphoma. But also when looking at the nasopharynx, you want to consider

9:32

the possibility of a nasopharyngeal carcinoma, which can also cause a lytic

9:37

clival mass. So when you look at the nasopharynx, these nasopharyngeal tumors

9:45

often occur in young patients and they don't have to have this amount

9:48

of soft tissue. This is sort of a really impressive case,

9:52

but obviously, sometimes you can just have a little bit of soft tissue

9:55

in the nasopharynx, usually off to one side

9:58

in the region of the fossa of Rosenmüller. Remember that if you're trying

10:02

to differentiate these tumors from say lymphoma or other tumors, you're

10:07

going to also look for things like perineural tumor spread.

10:11

And as in this patient, it's coming through the eustachian tube and into

10:15

the middle ear. It's completely destroying the pterygopalatine fossa and

10:22

involving V2. But you'll also look for a fairly characteristic pattern of

10:26

lymphadenopathy in these nasopharyngeal carcinomas. Remember, they can go

10:32

have lymphadenopathy spread to the retropharyngeal and often upper neck

10:38

nodal stations, including level IIa, level IIb, and even level V, and often

10:44

bilaterally. Lymphoma can also have lymphadenopathy, but it's usually a

10:50

little bit more homogeneous lymphadenopathy as opposed to lymphadenopathy

10:54

with carcinoma, which can have more necrosis. So those are some of the

10:58

ways you can help differentiate those. But sometimes you can't tell and

11:02

you need to get tissue. Again, you can see how nasopharyngeal carcinoma

11:07

is relatively T2 heterogeneous and hypo intense. So you would not put chordoma

11:13

or chondrosarcoma in that differential. You really want to... Something

11:17

that's more T2 hypo intense is going to be what we talked about,

11:24

either nasopharyngeal carcinoma or metastasis, or if it's really dark, lymphoma

11:30

or plasma cytoma.