0:00

This is a 57-year-old woman with

0:02

a mass that sits around, above,

0:06

and maybe in the pituitary gland.

0:08

The pituitary looks a little juicy, don't

0:09

you think, in the sagittal projection?

0:11

It does.

0:12

Yeah.

0:12

Clearly, though, there's a

0:13

different signal of this component

0:15

compared with the pituitary gland.

0:17

Let's make it even a little bigger.

0:19

And our mass looks completely separate,

0:22

like you could peel it from the brain.

0:24

It doesn't look like it's

0:25

infiltrating the brain.

0:26

So you have to favor, I think,

0:27

an extra-axial location.

0:29

And the real question now is

0:32

Is it involving the pituitary?

0:34

Is it coming from the pituitary?

0:36

Uh, or is it growing down from above?

0:39

I think your first, your

0:40

first impression is what?

0:42

My first impression is that

0:43

it's coming from above.

0:44

The mass is centered right, uh, the

0:46

majority of the mass is centered

0:47

along the planum sphenoidale.

0:49

Yeah, if I put my arrow right in the

0:50

middle of it, right there, I mean, you

0:52

know, that's not where the pituitary is.

0:54

Although, admittedly, this part is,

0:56

gives you some mass effect and the

0:57

pituitary gland looks a little prominent.

0:59

On the axial T2.

1:01

Uh, here is the mass encasing

1:03

the left carotid artery.

1:04

We can scroll up a little bit and see

1:06

just how large and heterogeneous it is.

1:08

It looks like it's, uh, performing some

1:10

compression and defacement of the A1 segment

1:13

of the anterior cerebral artery, along

1:15

with the proximal middle cerebral artery.

1:17

And then as we go down a bit

1:19

towards the pituitary gland, the

1:21

pituitary gland is still big.

1:23

We do see both carotid arteries.

1:25

Then we go to the coronal projection, and

1:27

a lot more information comes into play.

1:29

Um, pay no attention to these, uh, bilateral,

1:32

if you will, these bilateral, territorial, or

1:35

frontotemporal, sphenoidal, sutural meningiomas.

1:39

Uh, they're typical, you know, they

1:40

have that linear, uh, growth pattern on

1:43

both sides, that dural growth pattern

1:44

with a little bit of a dural tail.

1:46

Let's focus on this lesion right here.

1:49

It is very intimate with the upper border of the

1:51

pituitary gland, but you can separate it from

1:53

the stalk, and you can actually separate it,

1:56

if you look very carefully, I'm gonna make it

1:58

even bigger, from the pituitary gland itself.

2:02

Sometimes we use a little structure called the

2:03

pituitary tuft, which I don't see very well

2:06

here, which is a tuft of vessels in the middle

2:08

of the gland to see if the gland is infiltrated.

2:11

Um, it's not, although it would be nice

2:14

to see the tuft directly in the midline.

2:16

Still, our lesion is above it. There's a

2:19

plane of separation, right there, between

2:23

our lesion and the pituitary gland.

2:25

And then our lesion is growing over

2:27

the carotid siphon, but is it, is

2:30

it entering the cavernous sinus?

2:32

That's an important question.

2:33

What do you think?

2:34

I think it's sitting right

2:35

above the cavernous sinus.

2:36

Yeah, I mean, the cavernous sinus would be

2:38

more down in here. I mean, that's probably

2:41

one of the cranial nerves, maybe the third

2:43

cranial nerve, right there. These little

2:46

speckles are located in the cavernous sinus.

2:49

And when you have infiltration, you'll

2:50

lose that normal speckled appearance of

2:53

the nerves that course through there.

2:55

Uh, nerve 3, V1, first branch of

2:58

trigeminal nerve, V2, second branch of

3:00

trigeminal nerve, the 6th nerve, and so on.

3:03

So, the speckling of this area is preserved.

3:05

We don't have bulging along

3:07

the lateral dural wall.

3:09

We don't actually see the mass go into the dura.

3:11

We don't see it circumscribing

3:13

the carotid artery.

3:15

We don't see it on the lateral

3:16

side of the carotid artery.

3:18

All of those signs mitigating against the

3:21

diagnosis of cavernous sinus invasion.

3:23

Now we're in the anterior cranial fossa.

3:26

And, and you can get some really

3:27

impressive bone changes there.

3:29

What are some of the bone changes

3:30

that are associated with big anterior

3:33

cranial fossa, uh, meningiomas?

3:35

There's one in particular I know you like.

3:37

Yeah, so one thing that can happen is, uh,

3:39

you get an intense hyperostatic reaction,

3:42

which can retract some

3:44

of the bone and lead to a

3:45

thing called pneumosinus dilatans.

3:47

Uh, typically this happens only with the

3:50

floor of the anterior cranial fossa meningiomas.

3:52

So what is pneumosinus dilatans?

3:54

Sounds fancy.

3:55

It is fancy.

3:55

It's actually all it is is just

3:57

extension or expansion of the

3:59

sinuses due to the bone.

4:01

Sure.

4:01

And, and, you know, as radiologists, you

4:03

probably learned about that in the

4:05

syndrome known as Dyke Davidoff Mason syndrome,

4:08

uh, but we'll set that aside right now.

4:10

Pneumosinus dilatans is

4:11

associated with that condition.

4:13

Uh, the brain is

4:15

often smaller on that side.

4:18

And they may or may not have seizures.

4:20

So you don't think about pneumosinus

4:21

dilatans associated with meningioma.

4:24

Um, you can get lytic lesions.

4:25

You can get, as you said, hyperostatic

4:27

lesions that can mimic Paget's

4:29

disease or fibrous dysplasia.

4:31

And those are in the differential diagnosis.

4:33

Now if we just stop for a moment

4:35

and we look at the table.

4:37

So I'm gonna, I'm gonna take the

4:38

table of the skull right here.

4:40

Here's the inner table right there.

4:42

Here's the outer table, and then in

4:45

between we have the diploic space,

4:47

which I'm going to make orange.

4:49

So now I got orange in the

4:50

middle, and the diploic space.

4:52

So what does meningioma typically do?

4:55

Well, classically, it will

4:57

hit the inner table.

5:00

And I'm using gray here because

5:01

you see it kind of blends with the brain.

5:06

That's not the only type of

5:07

hyperostosis you can get.

5:08

You can actually get it on both sides.

5:10

So you wipe out that thin,

5:12

dark line of the outer table.

5:14

And it just becomes this large

5:17

gray or dark gray area and starts

5:19

to encroach on the diploic space.

5:22

There are times when it will actually

5:24

completely wipe out the diploic space too.

5:27

And there's also a scenario where it can even

5:30

be in the diploic space and spare both tables.

5:33

So you could have something like this.

5:35

Outer table, inner table.

5:37

And the inner table is spared, yet

5:39

the meningioma itself creates a reaction

5:41

in the diploic space, usually a sclerotic

5:44

one, and spares the tables themselves.

5:47

So those are some pretty interesting

5:48

variations that occur with meningioma.

5:51

And when you get this, it

5:52

looks like a sclerotic met.

5:54

When you get that, it looks like

5:55

some lesion that's wiping its way

5:57

through the calvarium, and

6:00

it makes you worried about more aggressive

6:02

things like lymphoma, melanoma, and

6:04

hemangiopericytoma, and metastases.

6:06

So let's move on from this very interesting

6:09

case, a skull-based meningioma with a

6:11

few daughter meningiomas in the petroclival

6:14

regions and take on something else, shall we?

6:15

Let's do it.

6:16

Okay.