0:00

This was an example of a patient that had bilateral

0:05

enhancing lesions involving both orbits.

0:09

And if you look at this image here on the left hand side, um, Courtney,

0:13

you can see my, uh, arrow, right? Yes. Okay.

0:16

So you can see this abnormal enhancement. This abnormal enhancement is,

0:20

it's actually within the muscle cone itself. So this would,

0:23

if you will be a true intracon lesion. And then on the right hand side,

0:28

a part of this is intracon, but there's also a part that's if you will,

0:32

extending extra conal and also involving the medial portion of the,

0:35

of the orbit. Now, in this particular case, um,

0:40

there are a couple things that can give you this differential diagnosis.

0:43

So there's, when I work through a case like this,

0:47

the things that I start to think about are my differential would be, um,

0:52

lymphoma, I would think of pseudotumor.

0:56

I would think of IgG four associated disease. I would think of sarcoidosis.

1:01

And then I would think of,

1:02

of what we used to call Wagners is poly polyangiitis, granulomatosis,

1:08

um, s So those are the things that, that I would think about. Now,

1:12

how can we help kind of separate those two out?

1:16

So what I like to do is try to get as much history as I can. And if,

1:20

if I know the patient, ha if the patient has a lot of orbital pain,

1:24

like really screaming orbital pain along with chemosis,

1:27

then that's gonna drive me to the diagnosis of, of pseudotumor.

1:32

Now, I think there is a D W I sequence in here. Uh,

1:36

so lemme pull that up. D diffusion weighted sequences.

1:41

What's sort of like the cur what's in vogue right now is that if you look at the

1:44

a d C maps, and let me find the a d C maps here,

1:48

I think they're in here somewhere. Uh, let's see.

1:52

There it is. So if you look at the a d C maps,

1:59

you can see that the A d C oh no, it's very sensitive.

2:04

There we go. Um, you can see that there's actually low signal on the A D C.

2:09

So what has been written is that lymphoma is associated with

2:14

reduced a d C. Now,

2:17

what I wanna make sure that you understand as a following is that if you see any

2:21

orbital lesion and there's decreased a d c,

2:23

that does not necessarily mean that the abnormality is lymphoma.

2:27

But if you are considering lymphoma and the a d C is reduced,

2:31

and that is supportive of the diagnosis of lymphoma, because if, for instance,

2:35

if this was metastasis, this would also have a decreased a D C,

2:40

but clinically the patient has no history of a primary lesion and there's no

2:44

concern about metastases,

2:46

then this decreased a d c can lead to your differential diagnosis

2:51

that you're dealing with, that you're dealing with lymphoma.

2:54

So in this particular case, um, this was an example

2:59

Of lymphoma. So what I want to do is, um,

3:04

give you a, a quick, uh, again, a little five, five,

3:07

a couple minute thing on some of these lesions, uh, lymphoma and pseudotumor,

3:13

et cetera. So let me bring up that PowerPoint. So when we start to,

3:17

to look at, I think I just showed this slide here again,

3:20

this was that thyroid ophthalm osteopathy versus the pseudotumor. And again,

3:24

we talked about this pseudotumor compared to thyroid, ophthalm osteopathy,

3:28

it tends to involve the muscle tendon. Now, one of the things, let go back,

3:32

let me go back to this one here. So, sorry, this is,

3:35

this is actually where I wanted to be here. So this,

3:38

these are examples of lymphoma. So how do we kind of make the,

3:42

the diagnosis of lymphoma? So I can tell you in my, in my practice, so you know,

3:46

I have an academic practice and, and a clinical practice. And the most common

3:52

entity that I've seen involving the retrobulbar region, the community.

3:56

So if you're not in an academic practice,

3:58

but you're in a community and you see something like this,

4:01

the most common thing that I've actually run into is lymphoma.

4:05

So lymphoma tends to be, um, densely enhancing on ct.

4:09

It can give you this sort of iso intense, uh, uh, intermediate attenuation.

4:14

And what it tends to do also, it sort of surrounds the nerve.

4:17

Now it doesn't necessarily compress the nerve,

4:20

but it sort of surrounds the nerve.

4:22

And you can see how it's sort of infiltrative,

4:24

it's sort of infiltrating this in the sense it kind of seeps into all the small

4:28

little crevices and there's not really any associated with bone erosion,

4:33

uh, with it. So this is the a d C value, and you can see there's decreased a d,

4:38

C. And if you see that, then that can suggest that you're dealing with lymphoma.

4:42

Now, when it comes to pseudotumor,

4:44

there's actually different types of pseudotumor. And this is where for me,

4:48

it gets a little bit confusing in the sense that pseudotumor,

4:53

the entity has been around for a long time. And from a pathological standpoint,

4:57

when they use the term pathologists, use the term pseudotumor.

5:00

Oftentimes they're not really sure what it is.

5:03

And sometimes if they're not sure what it is,

5:05

they'll go ahead and call it pseudotumor. Now,

5:08

pseudo tumors can be classified based on the morphology that we see

5:13

on imaging.

5:14

So there's actually six types of pseudo tumors based on the morphology.

5:19

So if we have a pseudotumor that's involving the lateral rectus muscle,

5:22

then this is referred to as myotic pseudotumor.

5:26

If we have pseudotumor here that's actually involving the sclera,

5:30

then this would be, uh, sclerotic neut pseudotumor.

5:34

If you have the pseudotumor that's involving the nerve and surrounding the

5:37

nerve, then this would be considered perine retic pseudotumor.

5:41

If it involves the lacrimal gland as it seen here,

5:43

this would be the ral type of pseudotumor.

5:45

If it's kind of involving everything in the orbit,

5:48

this is sometimes referred to as a diffuse pseudotumor. And then, um,

5:52

then if you, um, have pseudotumor that's extending into the cavernous

5:56

Sinus, then this is what we refer to as OSA hunt.

6:00

So there's actually six different types of pseudotumor just based on the

6:04

morphology and the extension.

6:07

And these patients typically present with a lot of orbital pain.

6:12

Now, this disease entity is IgG four associated disease. And again,

6:16

this was sort of, kind of came into vogue in the mid two, 2000 tens.

6:21

Between 2010 and 2020,

6:24

we became aware of this IgG four associated disease. Now,

6:28

this is a distinct entity. Um,

6:31

it's the way you make the diagnosis is through histological analysis,

6:36

and it's unclear whether this is a primary disease or versus a response.

6:40

And about 25 to 50% of quote unquote pseudotumor is

6:45

actually IgG force associated disease.

6:48

And typically the symptoms are painless and an enlarging mass.

6:52

And so many of these things in the head and neck that we would call pseudotumor

6:57

or things like T'S disease or kuttner's disease, um,

7:01

these are now sometimes felt to be as due to IgG four associated disease.

7:05

So even things like Hashimoto's. But the, the,

7:09

the thing that I notice, um, when I compare an academic versus a a,

7:14

a private practice is that if you're in an academic institution,

7:18

the disease sometimes is already considered.

7:21

So they will go ahead and test for, um,

7:25

they will go ahead and test for IgG four in the serum levels.

7:29

But oftentimes in the community,

7:31

what I end up seeing is that I'll call up the ophthalmologist and I'll say, Hey,

7:35

you know, what did the path turn out to be? And they say, well,

7:37

it was two pseudotumor. And then I'll say, well, did you test for IgG four?

7:41

And they said, no,

7:42

we didn't test for IgG four because that's not in our regular armamentarium.

7:46

So my point is that if you do see the path come back as pseudotumor,

7:50

one of the things that you should always ask for is did they actually test for

7:55

IgG four associated disease? So these are all forms of pseudotumor.

7:59

This is pseudotumor that was involved in the medial rectus,

8:02

the superior oblique, and, and the superior rectus.

8:05

This was pseudotumor involving the, uh, lacrimal glands.

8:09

And this was pseudotumor extending into the orbital apex,

8:12

into the cavernous sinus, and then also had this, this, this dural involvement.

8:17

So, uh, I think we did have a question here.

8:19

I think the question was how did dcra cystitis versus lacrimal pseudotumor how

8:24

to differentiate? Um, so javid, it's a great question. Um,

8:30

just based on the imaging findings alone,

8:32

it's really hard to differentiate between quote unquote dcra cystitis will be,

8:37

which will be an inflammation versus lacrimal pseudotumor.

8:40

The way that you can differentiate is potentially based on how the patients

8:45

present if they have pain. So in general, if they have a lot of orbital pain,

8:49

that would be suggestive of lacrimal pseudotumor. But if it's dcra cystitis,

8:54

then

8:54

They may not have as much pain. The other thing that, um,

8:59

that I have seen is that if you true have a two D acro cystitis,

9:04

which is involving the lacog gland,

9:06

then it really should be isolated to the lacm gland as

9:11

opposed to pseudotumor, which can be multifocal.

9:15

So what I would do is make sure you look at your search pattern and you look for

9:19

multiple foci, because if you have multiple foci of this abnormality,

9:23

then that would mean more consistent with, um,

9:26

pseudotumor as opposed to daco cystitis. Um,

9:30

can pseudotumor cause venous thrombosis? So another good question.

9:34

So

9:37

I would say that pseudotumor can probably cause compression of the venous sinus,

9:42

but if you actually look of the occlusion or

9:47

thrombus within the superior ophthalmic vein,

9:50

as you would see in something like cavernous sinus thrombosis,

9:53

and I don't think pseudotumor causes that because pseudotumor is more of a,

9:58

a slow term progressive process as opposed to an acute process.

10:02

So I think if there is anything that's involving the superior thalmic vein,

10:06

it probably would be more chronic as opposed to acute.

10:11

Okay, good. Yeah. So, uh, yeah, that's a really great question.

10:14

I'm glad you've mentioned that. So are there any ways to tell, and,

10:17

and the answer is yes. So let me, um,

10:21

let me get out of this and, and I'll show you exactly what I mean.

10:25

So when you show the case of,

10:28

of lymphoma in this particular case,

10:31

yes it does sort of look like meningioma, but if you look at the Coronas, no,

10:35

notice how this is a little bit more extensive.

10:38

But the real thing well I want you to pay attention to,

10:41

and I'm glad you asked the question,

10:42

is that the caliber of the optic nerve in lymphoma tends to

10:47

be preserved. And again,

10:49

the only way I can tell you this is sort of like looking at this over many

10:52

years, but lymphoma, again,

10:55

it's not really a hard compressive lesion because it's a rounding.

10:58

It's really arising from the soft tissues within the orbit itself.

11:04

Now if I go back and I look at this case,

11:08

so this is an example again of a retrobulbar mass that really looks sausage

11:12

shaped and you say to yourself, well this could be an optic nerve glioma,

11:16

could it be meningioma, could it be lymphoma, et cetera.

11:19

But this actually turns out to be meningioma.

11:22

Now the thing about the meningioma is that you've heard about the tram track

11:25

sign. So what meningiomas do is that they actually arise from the dural sheets

11:30

surrounding the orbit and they compress the optic nerve.

11:33

So notice how the optic nerve is actually compressed. So for me,

11:37

the way that I can differentiate meningioma from other entities

11:42

such as this, so this is an example of sarcoidosis, is yes,

11:46

there is enhancement here involving the C S F and the dura,

11:50

but notice how the caliber of the optic nerve

11:52

Is maintained. So for me, the key thing is to look at the caliber.

11:56

And if I see something that's involved in the optic nerve,

11:58

but that underlying optic nerve is narrowed,

12:02

then that's how I suggest a diagnosis of meningioma.

12:05

There was one case that, um,

12:08

that I've seen that was called lymphoma,

12:11

but it actually turned out to be meningioma.

12:13

You could actually tell because the nerve sheath was the,

12:15

the optic nerve was narrowed. So hopefully that answered your question.

12:20

I wouldn't make a list of everything that's decreased a, D, C,

12:23

and then start off with the A D C, I would suggest

12:28

coming up with what you think the diagnosis is based on the

12:33

non a d C images

12:36

and then see if the a d C is supportive of any of those entities.

12:42

Because what ends up happening is that you sort of focus on one sequence and the

12:46

next thing you know, you're like, well, 10 things can be, have decreased a, D,

12:51

C, and then you get confused.

12:53

So I always use a d c as a more confirmatory sequence as opposed to the primary

12:58

sequence. So the thing about things like chondro sarcoma, yeah,

13:02

chondro sarcomas can be low on a d c,

13:05

but is that because the density of the cells is really dense or is it because of

13:09

the calcification? And then then you'll say, well, you know what,

13:13

what about chondro? What about uh,

13:16

mixed con chondro sarcomas that have more of a chordoma

13:20

matrix?

13:21

'cause they can be mixed and then all of a sudden you kind of get confused

13:24

because these are not homogeneous tumors.

13:27

So I always use a d C as confirmatory.

13:29

So I look at everything else and then in the back of my mind, I know, well,

13:33

an abscess can have restricted diffusion and I know that more aggressive tumors

13:38

can have restricted diffusion. So if I'm looking at something and I'm like, Hmm,

13:43

there's the mass, what are the, all the imaging characteristics? And I'm,

13:46

I'm still trying to figure out, hmm, could this be benign or malignant?

13:49

Then I look at the ADCs and if it's decreased a D C and it's a good quality a c

13:53

c, then that drives me to suggest that I'm looking at more of a malignancy.