0:02

Hello, and welcome to Noon Conference hosted by Modality.

0:05

Noon Conference connects the global radiology community through free, live

0:09

educational webinars that are accessible for all and is an opportunity to

0:13

learn alongside top radiologists from around the world.

0:16

Today, we are honored to welcome Dr.

0:18

Mohit Aggarwal for a lecture entitled Salivary Gland Masses.

0:22

Dr. Aggarwal is an associate professor of neuroradiology and program director of

0:26

Neuroradiology Fellowship Program at the Medical College of Wisconsin.

0:30

He is a passionate educator and recently received the A3CR2

0:34

Outstanding Teacher Award from the AAR.

0:37

As well, he founded the Cortex Club, an online community that enhances

0:40

neuroradiology education through weekly quizzes, video lectures, and

0:44

sessions by world-renowned educators.

0:47

His clinical and research interests include head and neck and dementia imaging, and

0:51

he's actively involved in multiple societies.

0:54

At the end of the lecture, please join him in a Q&A session where he will address

0:57

questions you may have on today's topic.

0:59

Please remember to use that Q&A feature to submit your questions so we can get to

1:03

as many as we can before our time is up.

1:05

With that, we are ready to begin today's lecture. Dr.

1:07

Aggarwal, please take it from here.

1:11

So we're going to be talking about salivary gland masses.

1:14

I wanted to start with three simple images.

1:18

So here's our first image. And when we look at this mass

1:22

in this deep neck space, we wonder whether this lesion

1:26

comes from the parotid space, comes from the parotid gland.

1:29

Because the first thing that we should always try to look for or try to

1:33

see is localize the lesion. Localize the lesion

1:37

to where it's originating from. Is this from the parotid space?

1:40

Is it actually arising from the parotid gland itself?

1:43

Because even when we know that it's arising from a

1:47

particular space, the spaces of the salivary glands, the parotid space,

1:51

submandibular space, sublingual space, there are other structures that are

1:55

present in those areas. So our first

1:59

question should always be whether or not we are dealing with a

2:03

lesion that is of salivary gland origin and which space it is

2:07

arising from.

2:08

Then, the second image is this image, and we

2:12

look at this lesion that is probably in the parotid space,

2:16

and we are wondering whether the imaging

2:19

characteristics of this lesion help us to hone down into the

2:23

differential diagnosis or the final diagnosis.

2:26

And then we have this image where we again see this mass in the right

2:30

parotid region, and we are wondering whether this lesion is a benign

2:33

lesion or a malignant lesion. And if there are features there that

2:37

could help us differentiate a benign lesion from a

2:41

malignant lesion. So with these three simple images, I have

2:45

three simple objectives for today's talk.

2:49

We are going to learn to distinguish salivary origin tumors from other

2:52

lesions in the region.

2:54

Then we are going to use imaging characteristics to develop a differential

2:58

diagnosis, possibly the diagnosis, final provisional

3:02

imaging diagnosis. And then we are going to learn to distinguish

3:06

benign lesions from malignant lesions.

3:09

So, when we talk about the salivary glands, there are, of

3:13

course, three major salivary glands.

3:15

That is the parotid, the submandibular, and the sublingual glands.

3:19

But as we all know, there are multiple numerous minor salivary

3:23

glands that

3:24

sort of line the aerodigestive mucosa everywhere.

3:27

So there are minor glands everywhere along the aerodigestive mucosa,

3:32

and lesions can arise from those glands that are elsewhere

3:35

from the major salivary glands. So here's the

3:39

answer to one of the first questions, or one of the answers to the first question

3:43

is that how do we localize a parotid space lesion?

3:47

The parotid space is one of the spaces in the deep neck, which is

3:51

surrounded by other spaces, the masticator space, the pharyngeal mucosal

3:55

space, carotid space. And all these spaces are actually

3:59

around this particular space in the deep neck, which is

4:02

the parapharyngeal space right here.

4:04

This triangular space of fat is the parapharyngeal space.

4:09

The masticator space is anterolateral to it.

4:12

The parotid space is sort of lateral or posterolateral to

4:16

it. The carotid space is posterior to it, and the pharyngeal mucosal space is

4:20

medial to it. And so the displacement of this parapharyngeal space

4:24

fat can usually tell us which space a particular

4:28

lesion is arising from. So for example, this lesion, which is in the parotid

4:32

space, is moving or displacing this parapharyngeal

4:36

space fat anteromedially, and that's how we know that we

4:40

are dealing with a parotid space lesion.

4:42

Now, this lesion, which is in the masticator space, is pushing this parapharyngeal

4:46

space fat posteromedially because of where it's located.

4:50

A pharyngeal mucosal space lesion is going to displace this laterally, and a

4:54

carotid space lesion is going to displace this parapharyngeal space fat

4:58

anteriorly. And this is one of the major

5:04

clues as to the origin of a parotid space mass.

5:09

Now, what are the different structures that are in the parotid space?

5:11

Of course, we have the parotid gland, which is the major component of the parotid

5:15

space. But that's not

5:18

it. There are other structures within the parotid space, of which lymph

5:22

nodes are a major component. Lymph nodes of the neck

5:26

develop prior to the development of the parotid gland, and

5:30

therefore, when the parotid gland develops, these lymph nodes get enveloped

5:34

into the parotid gland. So lymph nodes are a major other component of

5:38

the parotid space. Then, of course, we have the facial nerve.

5:41

We all know it exits from the stylomastoid foramen and

5:45

divides within the parotid gland.

5:48

So the facial nerve is an important component.

5:49

And then we have vessels, of which

5:52

of note is the retromandibular vein, which is sort of just

5:56

posterior to the angle of the mandible.

5:59

And the position, because we cannot see the facial nerve very well on all

6:03

imagesThe retromandibular vein is used as a surrogate

6:07

for the plane of the facial nerve. So,

6:10

for example, we can see the retromandibular vein here, and that is used

6:14

as a surrogate for the location of the facial nerve.

6:17

So keep in mind that there are other structures within the parotid space that could

6:21

potentially

6:24

lead to other lesions.

6:27

Then again, trying to localize the lesion.

6:30

Here's a lesion here in the neck, and we are wondering which space this

6:34

lesion is arising from.

6:36

It could be in the submandibular or the sublingual space because those are the

6:40

spaces in this region. But there's one structure that really helps us, and that

6:44

is the mylohyoid muscle, which arises from the mylohyoid

6:47

ridge and goes towards the hyoid bone.

6:51

And lesions that are inferolateral to the mylohyoid muscle

6:55

are in the submandibular space, and lesions that

6:59

are superomedial to the mylohyoid line are in

7:03

the sublingual space. So the mylohyoid muscle really is the

7:07

landmark between the submandibular space and the sublingual space, and their

7:10

position can therefore tell us which space lesion we

7:14

are dealing with. As to the anatomy of the submandibular

7:18

and sublingual spaces. Submandibular space, there is not

7:22

much going on in the submandibular space besides the submandibular gland.

7:26

We do have lymph nodes in the submandibular space, so the level 1A and

7:31

1B lymph nodes are in the submandibular space.

7:33

But they're slightly different from how we see the lymph nodes in the parotid

7:37

space, where the lymph nodes are actually within the substance of the parotid

7:40

gland. Here, the lymph nodes are outside the

7:44

substance of the submandibular gland.

7:45

They're just there within the fat.

7:49

And then we have the various branches of the external carotid artery that

7:53

are in the submandibular space as well.

7:55

And then we have veins and loose areolar tissue.

8:00

As far as the sublingual space, sublingual space is slightly busier

8:04

compared to the submandibular space.

8:06

And to sort of know the lay of the land, there are three muscles that we should

8:10

always sort of look for when we are trying to look at the sublingual

8:14

space. The first of

8:16

which is the mylohyoid muscle, which we already talked about.

8:19

This muscle, which is arising from the mylohyoid ridge of the mandible,

8:23

is the mylohyoid muscle. Then we have the hyoglossus

8:26

muscle, which is the next muscle over towards the medial

8:30

aspect. That's the hyoglossus muscle.

8:33

And in the center, we have the genioglossus muscle.

8:35

So that's the genioglossus muscle. So this sort of gives us the lay of the land.

8:40

Then the sublingual gland within the sublingual space is

8:44

this anterior glandular tissue. So in the anterior

8:48

portion of the sublingual space is the sublingual salivary

8:51

gland. Then we have other structures. We have the submandibular duct.

8:55

The submandibular gland, which lives in the submandibular space, a

8:59

component of the submandibular gland actually extends into the

9:02

sublingual space. So that's the sublingual portion of the

9:06

submandibular gland, and the submandibular duct arises from it and then

9:10

runs in the sublingual space to open into the floor of the mouth here

9:13

anteriorly. So the submandibular duct is in the

9:17

sublingual space. Then we have nerves.

9:20

We have three nerves basically in the sublingual space, the

9:24

lingual and the hypoglossal nerves, and the glossopharyngeal nerve.

9:28

So the lingual and the hypoglossal nerves are lateral to the hyoglossus

9:32

muscle, and then medial to the hyoglossus muscle, we have the

9:35

glossopharyngeal nerve. And then we also have the lingual artery within the

9:40

medial portion or in the space between the genioglossus and the

9:44

hyoglossus muscle. So besides the sublingual gland itself, there are so

9:48

many other structures that are in the sublingual space, and these structures

9:52

can also give rise to different lesions.

9:54

So when we are looking at a lesion in the sublingual space, it's not just

9:58

salivary gland origin lesions, but there are lesions that could arise from

10:02

other structures.

10:05

So with this basic

10:07

sort of anatomy and basic understanding of the lesions

10:11

within these salivary gland spaces, we now look at some cases.

10:18

So here is our first case. We have this lesion in the

10:21

deep space of the neck, and we can see that this

10:26

parapharyngeal space fat is anteromedial to this

10:30

space. So it looks like this lesion is in the parotid space.

10:33

Of course, you can see that it is extending into the deep lobe of the

10:36

parotid gland. So this is definitely a parotid space lesion.

10:40

If we look at the lesion itself, the lesion is sort of

10:44

well-defined, has very smooth margins.

10:47

There is no margin spiculation. There is no change in

10:50

the signal of the gland itself. There is no edema,

10:54

no spiculation within the gland. And it's a very homogenous kind

10:58

of lesion, with no spiculation. Very bright on T2,

11:02

almost CSF in density. And these kind of lesions that are T2

11:06

bright and show homogenous enhancement are very frequent

11:10

within the parotid gland, and this is simply a pleomorphic adenoma,

11:14

which is the most common benign tumor that you will

11:18

encounter in the

11:20

parotid gland. One thing to remember here is that the larger the

11:24

gland, there is more chances that you will be dealing with a benign

11:28

lesion, and the smaller the gland, there are more chances that you will be dealing

11:32

with a malignant lesion. So by far, the most common lesion that you

11:36

will see in the parotid gland that has

11:40

bright T2 signal, shows homogenous enhancement, has smooth margins with no

11:44

margin spiculation, maybe some lobulations, but no

11:48

infiltration or spiculation of the margins.

11:50

These lesions are almost always going to be these pleomorphic

11:53

adenomas.And here's another example of a pleomorphic

11:57

adenoma. On a CT, you will see that it has low density, very

12:01

well-defined margins, slightly lobulated, but still there is no

12:05

margin spiculation, there is no infiltration of the surrounding structures,

12:08

enhancement on the post-contrast images.

12:11

And again, another example of a pleomorphic adenoma, which is the most

12:15

common benign tumor of the parotid gland.

12:18

Here's another lesion. Again, very well defined.

12:21

You can see it extends to the deep lobe of the gland.

12:24

There is some enhancement. But this low T2 signal sort of makes me

12:28

pause a little bit. When there is low T2 signal within

12:32

a salivary gland lesion, you should always give it a pause

12:36

and try to look at other imaging characteristics.

12:40

In terms of other imaging characteristics, it's still well defined, there is no

12:43

margin infiltration, and although I'm a little bit suspicious,

12:48

this lesion still turned out to be a pleomorphic adenoma.

12:51

Again, reiterating the fact that most benign lesions or most

12:54

lesions in the parotid gland are going to be benign lesions and are going to be

12:58

pleomorphic adenomas.

13:01

Pleomorphic adenomas, although they are benign lesions, they

13:05

are notorious for being recurrent, especially they're

13:09

notorious for getting seeded in the surgical

13:13

bed. And when you have a history of a resected

13:16

pleomorphic adenoma and you see these bright bunch of

13:20

grapes type appearance in the surgical bed, always think about a

13:24

recurrent pleomorphic adenoma. Recurrent pleomorphic adenomas have this

13:28

characteristic bunch of grapes appearance.

13:30

They are bright on T2 weighted images, just like

13:34

pleomorphic adenomas are. But then, this is sort of

13:38

multi-lobulated bunch of grapes appearance. They enhance.

13:41

So when you see this in a person who's had a history of a resected pleomorphic

13:44

adenoma, always

13:49

suspect

13:50

recurrence of a pleomorphic adenoma.

13:53

Then this lesion here, again, it looks like this lesion is in the

13:58

parotid space, probably arising from the parotid gland.

14:01

The

14:02

parapharyngeal space fat is anteromedial to it.

14:06

If we look at the imaging characteristics of this lesion, however,

14:09

the deep lobe looks like there is some

14:13

T2 hyperintensity, but as we go laterally, this is sort of

14:17

hypointense on T2. If I look at the margins of this lesion, the

14:21

margins are not very well defined. They are indistinct at certain places.

14:25

And here, when we look here on the post-contrast images, it looks like the margins

14:29

are very sort of infiltrative and spiculated.

14:32

So this, if you have a pleomorphic adenoma that is present

14:36

for a long time and it changes suddenly, you see enlargement of that

14:40

pleomorphic adenoma, if there is hemorrhage into it, although not

14:44

very common,

14:46

carcinoma disc conversion of pleomorphic adenoma is not very common.

14:50

But if you see those imaging characteristics and if you see

14:54

indistinct margins, low T2 signal hemorrhage, then you

14:59

can suspect a carcinoma ex-pleomorphic adenoma, which

15:03

is basically a malignant conversion of a pleomorphic adenoma.

15:08

Then, another lesion here in the parotid gland.

15:12

There's this lesion here in the superficial lobe of

15:16

the right parotid gland. It looks well defined, maybe

15:20

some lobulated margin, but again, there is no margin spiculation.

15:24

There is no indistinct margins. There is probably some

15:27

cystic change here

15:30

on this lesion. So there is some heterogeneity, some kind of cystic

15:33

change. We are still looking at this lesion.

15:36

And when we are looking at on the contralateral side, we see that there is another

15:40

lesion here on the left side, which has very similar imaging

15:43

characteristics to this lesion that we saw on the right side.

15:47

So again, very well defined,

15:49

some kind of cystic change. So this lesion is

15:53

multifocal. So multifocal lesions bilaterally in the parotid glands.

15:57

And if I told you that this person was an older person and has history of

16:00

smoking,

16:02

Warthin tumor should immediately come to mind because Warthin tumors

16:06

are present in older individuals, especially if they have

16:10

history of smoking.

16:11

They can be bilateral commonly, although not always.

16:16

They have benign imaging features, and sometimes they can have a cystic change.

16:19

So if you see a lesion that

16:23

looks benign,

16:25

has some cystic change, especially if they're multiple and have history of smoking,

16:29

suspect a Warthin tumor. This is another example

16:33

of bilateral Warthin tumors. This patient was also a smoker.

16:36

So bilateral lesions, and inferiorly, you can see that there is some

16:40

kind of cystic change.

16:43

Then what about this lesion? We have another lesion here in the left parotid

16:47

gland.

16:50

Very well defined, no infiltrative margins, and this is

16:53

entirely

16:55

composed of fat, and this is simply a lipoma in the

16:59

left parotid gland.

17:02

Then another lesion here. Here we have a lesion in the

17:06

superficial portion of the right parotid gland.

17:09

But when we look at this lesion, this lesion does not look very well

17:13

defined. At the deep portion of the lesion, I can't

17:17

even see the margins of this lesion.

17:20

So the margins are very indistinct on this aspect of the lesion.

17:23

So not a very well-defined lesion.

17:25

When I look at this T1 weighted image, I see some margin

17:28

spiculation. Look at all these spicules that are going into that

17:32

parotid gland parenchyma. So, when I see those kind of spiculations,

17:36

when I see these indistinct margins, immediately I start

17:40

suspecting something that is not completely benign.

17:43

Even the enhancement characteristics of this lesion, not very good.

17:48

There is heterogeneous enhancement. There is margin infiltration.

17:51

So immediately I'm suspecting that this lesion is not completely benign.

17:55

It could be some kind of malignant lesion.

17:58

And the most commonmalignant lesion that you will encounter in the parotid gland

18:02

is going to be a mucoepidermoid carcinoma.

18:05

So mucoepidermoids are most common malignant tumors of the parotid gland.

18:09

But as we move into the smaller glands, which is the

18:13

submandibular and the sublingual glands, there the most common

18:17

malignant lesions are going to be adenoid cystic cancers.

18:20

But in the parotid gland, most common

18:22

malignant lesions are mucoepidermoid carcinomas.

18:27

Then here are two other examples of mucoepidermoid cancers.

18:31

On the right side, you can see again, heterogeneous lesion with

18:35

margin spiculation, not very well-defined.

18:37

And in this lesion, you can see that this is associated with necrotic

18:41

lymphadenopathy. So mucoepidermoid cancers are associated with

18:44

lymphadenopathy. They are malignant.

18:46

They have all these malignant features.

18:49

Besides the lymphadenopathy, besides describing the lesion, the other things that

18:53

we should always try to see, try to describe is

18:56

how big is the lesion, whether or not there is extraglandular extension,

19:00

if there is perineural tumor spread, if there is osseous invasion or

19:04

not. So even though we might not come down to the histology of the tumor,

19:08

it's okay to simply suggest that you're suspecting malignancy in a salivary gland

19:12

tumor. And it's not always necessary for you to say it's a

19:16

mucoepidermoid or an adenoid cystic or a squamous cell.

19:19

But as long as you say that you suspect the lesion to be malignant

19:23

and you describe the lesion, if you

19:26

accurately measure the size, you say what the extent of the lesion is, and

19:30

you

19:32

pick up ancillary findings like lymphadenopathy, perineural tumor

19:36

spread, bone invasion, then that's completely okay because

19:39

differentiating malignant tumors one from the other can usually be

19:43

difficult.

19:45

Always look for lymphadenopathy, of course.

19:46

Mucoepidermoids are associated with enlarged lymph

19:50

nodes. Here's another lesion. So we have this lesion in

19:53

the left parotid gland. And again, you can see, not

19:57

very well-defined. There are spiculated margins, infiltrative margins.

20:02

As we look further and we look for perineural tumor spread, we

20:06

can see that there is infiltration of the fat in the stylomastoid

20:10

foramen. Compare it to the fat on the other side. This is normal.

20:13

That is what you're supposed to see, but here there is infiltration of fat,

20:17

loss of fat plane. That's not good, which means that the tumor is already going

20:21

into the stylomastoid foramen. On the bone windows, we can see

20:25

erosion of the facial nerve canal.

20:28

And as we go further into the skull base, there is widening of the facial nerve

20:31

canal here. You can compare it to the other side.

20:34

There is widening, and then there is enhancement on

20:37

MRI. So all this enhancement that you see along the facial nerve canal, there

20:42

is clear evidence for

20:44

perineural tumor spread here. So there is a lesion

20:49

in the left parotid gland with evidence for

20:52

perineural tumor spread and osseous invasion.

20:55

Adenoid cystic cancers are notorious for

20:59

perineural tumor spread, although any kind of cancer can cause perineural tumor

21:03

spread. Mucoepidermoids can also be associated with perineural tumor spread, and

21:07

so can be squamous cell cancers. But adenoid cystic cancers classically

21:11

have higher propensity for perineural tumor spread, and this tumor turned out to be

21:15

an adenoid cystic cancer.

21:20

Another parotid lesion here. You can see spiculated,

21:24

indistinct margins extending into the deep lobe of the gland.

21:28

On this MRI, you can see that there is asymmetric enhancement of the

21:32

V3 portion of the trigeminal nerve,

21:36

and this enhancement is going all the way through the foramen ovale into the skull.

21:40

So there is clear evidence for perineural tumor spread.

21:43

Now, classically, when we talk about parotid gland lesions, or when

21:47

we talk about perineural tumor spread in the parotid gland, we always think of the

21:51

seventh cranial nerve because the seventh cranial nerve divides within the parotid

21:55

gland. But you should always also remember that there is another

21:59

nerve that supplies the parotid gland and lives in the

22:03

vicinity of the parotid gland or in the substance of the parotid gland, and that is

22:06

the auriculotemporal nerve. Auriculotemporal nerve

22:10

deserves special mention here because auriculotemporal nerve is within the

22:14

parotid gland, and it can very well be involved in

22:18

perineural tumor spread in parotid lesions.

22:20

The auriculotemporal nerve lives in this area called the

22:25

stylomandibular tunnel, which is in between the styloid

22:29

process and the mandible. The stylomandibular tunnel is where the

22:32

auriculotemporal nerve lives. So when we are talking about lesions of the

22:36

parotid gland, we should always

22:39

remember that there are two nerves within the parotid gland.

22:42

One is the facial nerve, which we all know, but also the auriculotemporal nerve,

22:46

which is a branch of V3, lives in the parotid gland parent coma and could

22:50

be involved in

22:52

perineural tumor spread. So perineural tumor spread can extend along

22:55

cranial nerve

22:59

VII, but it can also extend along the V3 and

23:03

into the trigeminal nerve.

23:05

Now, here's another case, and I only put this case to

23:10

further

23:12

include diffusion imaging characteristics

23:16

of salivary gland lesions. Here we have a lesion in the

23:20

right parotid gland, some indistinct margins, but it definitely

23:24

shows low ADC. So although

23:27

diffusion-weighted imaging is not the only thing that

23:31

helps us to make a diagnosis, but if you see low ADC

23:35

characteristics in a

23:37

salivary gland tumor, then you know that you're dealing with hypercellularity, and

23:40

those lesions are more likely to be malignant lesions compared to lesions that do

23:45

not show low ADC. So besides the T2 imaging

23:48

characteristics, which can be dark

23:51

in malignant lesions, besides the margins, the margin spiculation,

23:54

infiltration, also take help of diffusion-weighted imaging, and if you see

23:58

that a lesion is low on ADC, you might

24:02

suspect

24:03

that that lesion could be malignant, more than if you weren't suspecting

24:07

it.Another lesion here in the

24:11

right parotid gland. Of course, it is involving the adjacent structures.

24:15

It is going into the deep lobe.

24:18

There is definite malignant characteristics to this mass.

24:22

What is this mass? I put this case here to, again,

24:26

reiterate that differentiating different malignant lesions of the

24:30

salivary glands is not very easy. This was a squamous cell

24:34

carcinoma.

24:36

So as long as you describe what the lesion is doing, as long as you describe that

24:39

there is indistinct margin with the masseter muscle, it is extending into

24:43

the deep lobe of the gland, it is probably involving soft tissues of the

24:47

ear canal. As long as you describe the lesion, that usually suffices

24:51

for management purposes. The final diagnosis usually depends

24:55

on histology. So if you can differentiate a

24:58

mucoepidermoid from an adenoid cystic or from a squamous cell and other lesions,

25:02

that's completely okay, as long as you describe the lesion well, as

25:06

you describe the extent of the lesion well.

25:10

Another lesion here. Very low T2

25:14

signal, as you can see here. It has

25:18

homogenous, avid enhancement. Again, it could

25:22

be anything. But when I see very low T2 signal, like I see here,

25:26

and I see homogenous, avid enhancement, lymphoma starts

25:30

becoming more and more of a possibility in my mind.

25:33

And this is what this lesion was. This was a

25:36

lymphoma of the parotid gland. Now, lymphoma can involve

25:40

the parotid gland in many different ways.

25:41

As I said earlier, there are multiple lymph nodes within the substance of the

25:45

parotid gland. So, those lymph nodes can get involved

25:49

in systemic lymphoma. So you can have systemic lymphoma and

25:53

parotid lymphadenopathy because of systemic lymphoma.

25:56

But lymphoma can also primarily involve the parenchyma of the gland

26:00

itself. And here you have non-Hodgkin lymphoma that is primarily involving

26:03

the gland of the parotid gland itself.

26:08

Then, here we have multiple lesions in the parotid gland.

26:12

They're showing central necrosis.

26:15

I just talked about the lymph nodes that can be seen in the parotid

26:19

gland. When you see that,

26:22

always sort of remember that there can be lymph nodes in the parotid

26:26

parenchyma. So metastatic lymphadenopathy can very well present

26:30

as multifocal masses within the parotid gland.

26:33

And this metastatic lymphadenopathy was simply because of this

26:38

skin cancer that was in the vicinity of the parotid gland.

26:42

So skin cancer here, and this is metastatic lymph nodes from the

26:45

overlying skin cancer.

26:48

Parotid lymph nodes, as I said, there are multiple lymph nodes in the parotid

26:51

gland. They are within the parotid and in the

26:56

soft tissues around the parotid.

26:58

They basically drain the external auditory canal.

27:02

They drain the skin of the cheek, and of the frontal

27:06

and the parietal scalp. So all these areas are drained into

27:10

the parotid lymph nodes. And lesions in all these

27:14

areas can lead to parotid lymphadenopathy.

27:17

They further drain into the level one and level two nodes.

27:21

They can be divided into several groups. They can be preauricular.

27:25

They can be superficial parotid. They can be deep parotid lymph

27:29

nodes. So, when you have a lesion in this location, always also look

27:32

in the deep lobe of the parotid because there can be lymphadenopathy

27:36

there. And then there can be subparotid lymph nodes.

27:39

So all these are different group of parotid lymph nodes.

27:43

Now, the parotid lymph nodes can be involved in systemic

27:47

lymphomas. This is a case of CLL with a

27:51

parotid lymphadenopathy, or they can be involved in local diseases.

27:55

So frontal scalp cancers, parietal scalp cancers, lesions of the external

27:58

auditory canal of the cheek, they can all lead to parotid

28:02

lymphadenopathy and present as parotid gland

28:05

lesions or parotid gland masses.

28:09

And then, of course, the lesions of the parotid itself.

28:11

So if there are cancers within the parotid gland itself, they can

28:15

be parotid lymphadenopathy secondary to

28:19

parotid lesions or parotid masses.

28:22

Then here's another cystic lesion in the

28:26

parotid gland. Looks like it's close to the superficial lobe of the parotid gland.

28:31

Is it really of parotid origin? At least on this axial image, it looks like it

28:35

could be of the parotid origin. But as we look at this

28:38

sagittal image, it looks like there is a sinus tract that is going

28:42

from the lesion itself into the external auditory canal.

28:46

And this lesion was not a parotid gland lesion, it was the first

28:49

branchial cleft cyst. So also remember that the first branchial cleft

28:53

cyst can present as a parotid lesion.

28:56

You closely have to look for that sinus tract if it's in the close proximity to the

29:00

external auditory canal. And if there's a sinus tract going into the external

29:04

auditory canal from the cystic lesion, especially

29:08

if these are younger individuals, suspect a

29:11

branchial cleft cyst.

29:14

Then this person has bilateral cystic lesions in the parotid gland

29:18

and has history of HIV. And when you have that,

29:22

think of this entity, which is benign LELs or lymphoepithelial

29:26

lesions of HIV. They can present as bilateral cystic

29:30

intraparotid lesions. So if there is history of HIV, you see that, suspect

29:34

benign LELs.

29:37

Another lesion here in the parotid gland.

29:40

Here avidly enhancing in the

29:44

superficial and the deep lobes. It's straddling both of these

29:48

lobes. You can see it here. This coronal image is

29:52

actually weird. Even though here it looks like it could

29:55

be arising from the parotid, but here this lesion is

29:59

extending into the facial nerve canal through the

30:03

stylomastoid foramen. So, we could suspect that this is a

30:07

malignant lesion with perineural tumor spread.

30:10

Perineural tumor spread can be this gross, but this is

30:13

the mass itself that's going into the

30:17

facial nerve canal. Of course, this is a rather difficult case,

30:21

but I've put this case here only to show you that the facial nerve

30:25

itself is present in the parotid gland parenchyma, and

30:29

lesions arising from the facial nerve itself can also present as parotid

30:33

gland masses. So this was a schwannoma of the facial nerve.

30:36

It isKind of difficult to make that diagnosis

30:40

prospectively, but this case is here just to show that lesions

30:44

of the facial nerve itself can present as parotid gland masses and these are

30:48

not primarily glandular masses.

30:52

Moving on to the submandibular lesion, submandibular

30:56

region.

31:00

Here we have a lesion in the

31:02

submandibular space. We can see it here.

31:05

It looks like it is within the gland of the parenchyma.

31:08

You can see this claw sign here. So this lesion is within the

31:11

substance of the right submandibular gland.

31:15

Looks very well-defined as low density on CT.

31:18

There is maybe mild enhancement. Again, benign characteristics.

31:22

Pleomorphic adenomas

31:25

can be there in the submandibular gland itself.

31:27

Of course, you should remember that if you see any margin spiculation,

31:31

there is more likelihood of a lesion

31:33

being malignant in the submandibular gland compared to the parotid gland, because

31:37

it's a smaller gland. But of course, pleomorphic adenomas can be there and are

31:41

pretty common in the submandibular gland, too.

31:44

But when you see this, when you see that there is, of course, this heterogeneous

31:47

appearance, looks very dirty, there is extraglandular

31:51

spread of disease, then you should suspect that we are dealing with a

31:55

malignant glandular lesion, and this was a mucoepidermoid

31:59

carcinoma of the submandibular gland.

32:02

Of course, mucoepidermoids are slightly less common in the submandibular

32:06

gland compared to adenoid cysts, but this one turned out to be a

32:09

mucoepidermoid. Of course, the lesions, you don't have to go into the

32:13

histology. You can just suggest that this looks malignant.

32:16

This looks like a malignant salivary gland tumor.

32:19

The more important thing to describe would be the extraglandular spread,

32:22

involvement of the skin, involvement of the bone, and if there is any kind of

32:26

perineural tumor spread.

32:30

Another lesion here in the submandibular region.

32:33

You can see the mylohyoid muscle. This is

32:36

inferolateral to the mylohyoid, so in the submandibular region,

32:40

of course, but we can see that the submandibular gland itself is pushed

32:44

posteriorly from this lesion. There is no change in the

32:47

glandular parenchyma, so probably this lesion is not arising from

32:51

the gland itself. This person had dental disease, and this

32:55

was simply a submandibular abscess secondary to dental disease.

33:00

Another lesion here in the submandibular

33:03

space, but again, very separate from the submandibular gland itself.

33:08

We also know that the other content of the submandibular

33:12

space is lymph nodes, so there can be adenopathy in the submandibular

33:16

region from oral cancers, from other cancers in the

33:19

region. So,

33:22

always know that there can be lesions other than submandibular

33:25

origin in the submandibular space, and this was submandibular adenopathy.

33:30

Another lesion in the submandibular space.

33:32

You can see that the submandibular gland itself is pushed posteriorly.

33:36

There is a well-defined plane between the lesion and the gland,

33:39

so this is not a lesion of glandular origin.

33:44

Very hyperintense on the stir image.

33:47

There is absolutely no enhancement.

33:49

This is enhancement of the adjacent vein, but the lesion itself does not

33:53

enhance. These kind of cystic lesions

33:56

are not uncommon in the submandibular and sublingual spaces.

34:00

When you see a cystic lesion in the submandibular or sublingual space, the things

34:04

to think about are ranulas, of course, but ranulas primarily arise

34:08

in the sublingual space, and this does not seem to have a sublingual space

34:12

extension. You can have dermoids and epidermoids.

34:14

They are also cystic lesions in this space.

34:17

The other lesion that is common is venolymphatic malformation, and when you see

34:20

this kind of multicystic appearance, some kind of septate

34:24

appearance with fluid signal non-enhancement, you should

34:28

suspect a lymphatic malformation or a venolymphatic

34:31

malformation, which is what this lesion was.

34:34

So these kind of lesions are also common in this location.

34:39

Another lesion in this area.

34:42

This seems to be superior to the mylohyoid

34:46

muscle, a cystic lesion.

34:48

Superior to the mylohyoid muscle in the sublingual space.

34:51

Completely cystic, no enhancement.

34:53

It does extend anteriorly and has this U-shaped configuration with

34:57

communication to the opposite side.

35:00

I just said when you see a cystic lesion in the sublingual, submandibular

35:03

spaces,

35:05

the things to think about are ranula, dermoid, epidermoid, venolymphatic

35:09

malformations. And this lesion has a very characteristic

35:13

U-shaped appearance in the sublingual space, and this is a ranula.

35:17

Ranulas do have communication to the other side.

35:20

Ranulas are basically retention cysts of the sublingual

35:23

gland. They can be localized in the sublingual space,

35:27

have this U-shaped configuration sometimes, but sometimes they can

35:31

extend along the posterior margin of the mylohyoid muscle

35:35

and extend into the submandibular space.

35:37

They always have this connection to the sublingual space, as you can see here,

35:41

which is a clue to their origin in the sublingual space.

35:45

But these kind of lesions that extend into the submandibular space or

35:49

dive into the submandibular space are known as diving or

35:53

plunging ranulas. So two kind of ranulas, simple, that are confined to the

35:57

sublingual space, or diving or plunging ranulas that extend into the

36:01

submandibular space around the posterior

36:04

border of the mylohyoid muscle.

36:10

Another lesion here in the sublingual space.

36:13

We see this kind of cystic lesion. At the

36:17

anterior end of the cystic lesion, we have this calcific focus.

36:21

So this is a stone in the submandibular duct, and this

36:25

cystic lesion in the

36:27

sublingual space is simply a massively dilated submandibular duct.

36:31

And if you remember from that slide of anatomy, we know that the submandibular

36:35

duct actually lives in the sublingual space.

36:37

So another differential for a cystic lesion in the submandibular space

36:41

is a dilated submandibular duct. Of course, this is a very

36:45

sort of dramatic example of dilatation.

36:47

Usually, the dilatation is smaller, but you can get cystic lesions that would be

36:51

dilated ducts in the sublingual

36:54

space.We are coming to a close here.

36:58

We have another sort of complex solid cystic

37:02

lesion that is in the submandibular space, but

37:06

also extending partly into the sublingual space.

37:09

It is interposed

37:11

between the mylohyoid and the genioglossus

37:14

muscles. As cystic

37:18

lesions in this region go, it could be ranula.

37:21

Of course, it doesn't look like a ranula, very multicystic, doesn't have

37:25

that U-shaped configuration. Could be a dermoid, epidermoid.

37:29

They don't enhance heterogeneously.

37:31

This lesion does enhance quite a lot.

37:34

It does have cystic spaces.

37:36

But just by its position as interposed between the mylohyoid and

37:40

hyoglossus muscles, we know that two nerves live in this location, the

37:44

lingual and the hypoglossal nerves.

37:47

This lesion is somewhat elongated and is along the

37:51

course of the lingual nerve. Of course, prospectively, we gave the differential of

37:55

a venolymphatic malformation and a

37:58

lingual nerve schwannoma in this case.

38:00

But finally, it turned out to be a lingual nerve schwannoma.

38:03

So again, a

38:07

suggestion that there can be other lesions of non-salivary gland

38:10

origin in the location where the salivary glands are present.

38:16

Another case here. Dr. Muzaffar was kind enough

38:20

to lend me this case.

38:22

Here we have a lesion well defined in the sublingual space.

38:25

You can see it is above the mylohyoid muscle, so it is in the sublingual space.

38:30

Very bright on T2, shows some enhancement.

38:34

When you see bright T2 lesions in the location of the

38:38

submandibular glands, you always suspect pleomorphic adenomas.

38:43

Again, remember that the smaller the gland, the more likely that

38:47

the lesion is going to be malignant, although this lesion does not look malignant.

38:51

The other thing is that this is not exactly in the location of the sublingual

38:55

gland, which is more anteriorly.

38:58

Bright T2 lesions besides pleomorphic adenomas, schwannomas tend

39:02

to be bright on T2. They show this kind of enhancement, kind of an

39:05

unusual location for a schwannoma, but remember that

39:09

there are nerves in that location, and schwannomas can arise from

39:14

those nerves. So this was, again, a sublingual schwannoma.

39:17

A beautiful case lent to me by Dr. Muzaffar.

39:19

But, again,

39:21

reiterating that there can be extraglandular lesions that

39:25

can be present in these locations.

39:29

Then minor salivary glands, more likely

39:33

to be malignant lesions arising from this space.

39:36

So, here we have a lesion from the palate,

39:40

kind of a lobulated lesion. Minor salivary glands are present

39:44

everywhere along the aerodigestive tract.

39:47

Palate is a common location for minor salivary gland tumors, and this

39:51

lesion is already associated with infiltration of the fat in the

39:55

periferingeal space. You can see that there is enhancement here, so there

39:59

is evidence for

40:01

perineural tumor spread, and this turned out to be an adenoid cystic cancer.

40:05

And here is a mucoepidermoid cancer in the posterior

40:09

palate. Again, a salivary gland origin tumor, coming from a

40:13

minor salivary gland. So,

40:16

again, it's not important for us to

40:19

say whether the lesion is adenoid cystic or

40:22

mucoepidermoid, as long as we suspect that the lesion is malignant.

40:26

Our job there is done. More importantly, our job is to

40:30

describe the lesion, the size, the extent, extraglandular spread,

40:33

perineural tumor, skin involvement, bone involvement.

40:36

Those are the things that are more important. And why are they important?

40:39

Because they are important for staging.

40:42

All these things, extraglandular tumor spread, perineural tumor, bone

40:45

invasion, these are the things that upstage salivary gland

40:49

tumors. So it's important for us to describe that because they are

40:53

used for staging of these lesions.

40:56

So, when we talk about the T staging, I'm not going to go into the details

41:00

of what is T1, what is T2, but the

41:04

points that upstage the tumor, we should always know what are the

41:07

things that could upstage the tumor.

41:09

Size in the different T stages, less than two, two to four, and

41:13

more than four are the different criteria that are used to upstage tumors.

41:17

Is the tumor confined to the gland itself, or is there extraglandular spread?

41:19

So if there is extraglandular spread, that's going to upstage the tumor.

41:22

So if there is extraglandular spread, always describe it.

41:25

If there is involvement of the overlying skin, if there is bone invasion,

41:29

if there is perineural tumor spread, involvement of the seventh nerve, if

41:33

there is skull base invasion, all these things are going to upstage the tumor,

41:37

so always try to describe these things.

41:39

As far as nodal stages go,

41:42

three centimeter, three to six centimeter, and six centimeter are the different

41:46

criteria that are used to upstage nodal disease.

41:50

Whether the lymph nodes are single or multiple, unilateral or

41:53

bilateral, or if they're ipsilateral or contralateral to the lesion itself,

41:58

that is also used in upstaging these tumors.

42:00

And then extranodal extension, very, very important.

42:04

Extranodal extension is the highest clinical nodal stage for

42:07

any tumor in the head and neck. So if you have evidence for extranodal

42:11

extension, always describe it because that's the highest nodal

42:15

clinical stage for any cancer. And then, of course, if there is

42:19

metastasis, if there is distant metastasis, always describe that.

42:24

So finally, if we are taking home a

42:27

checklist of how to describe

42:30

these salivary gland lesions, salivary gland masses.

42:34

Size is very, very important. Two centimeter, two to four, more than four.

42:39

Whether the lesion is

42:40

single or multiple. Single or multiple is important because Warthin's tumors can be

42:45

bilateral. Lymph nodes can be bilateral.

42:48

So it also helps us know

42:51

what kind of lesion we are dealing with.

42:54

Then if we are dealing with a malignant lesion, always describe the margins,

42:58

whether they're smooth versus spiculated or indistinct.

43:01

Look at the T2 signal. Dark T2 signal sort of is

43:05

concerning and could

43:08

indicate malignancy. If there is low ADC, of course,

43:12

that kind of tells us that we are probably dealing with a hypercellular

43:16

tumor.

43:18

Extraglandular extension, very, very important.

43:20

If there is involvement of skin, if there is bone erosion, skull base

43:24

involvement, all these things are important in staging tumors.

43:28

Perineural tumor spread is important.

43:29

And then if you're dealing with a malignant lesion, always look for

43:33

cervical lymphadenopathy.With this,

43:37

I want to thank you all for hearing patiently. I'm open for questions.

43:43

Thank you so much for that lecture, Dr. Agarwal.

43:45

There is a question in the Q&A box, if you can find

43:49

that at the bottom of your Zoom screen.

43:53

I have chat here.

43:54

Should be a box with a question mark in it.

43:57

Okay.

43:58

I can also read it to you if you want.

43:59

Yeah. Is there a histological connection between the salivary gland

44:03

tumors and bronchial tumors?

44:07

Well,

44:09

because salivary glands are present everywhere along the

44:13

aerodigestive tract,

44:15

there can be salivary

44:18

tumors in the bronchus too. So, yeah.

44:21

These kind of salivary gland tumors are

44:24

present

44:26

in the aerodigestive mucosa. So, yeah, you can have

44:30

these kind of tumors in the bronchus.

44:38

We'll wait one more minute. Sometimes it takes a second. Here we go.

44:41

There's another one.

44:43

Enlarged non-reactive lymph nodes are often seen on

44:46

ultrasound

44:49

at level 1A. What is the clinical significance of those

44:53

findings? How to be managed, monitored?

44:57

And this is sort of a whole different topic of lymph nodes.

45:02

We should, and I always tell this when I talk about

45:06

lymph nodes. Lymph node size is the weakest

45:10

criteria for describing a lymph node.

45:13

We do describe lymph nodes, as their size.

45:17

If they're jugulodigastric nodes, 15 millimeter is the cutoff.

45:21

If they're lymph nodes elsewhere in the neck, 10 millimeter is the cutoff.

45:23

If they're retropharyngeal nodes, eight millimeter is the cutoff.

45:27

But that is only the criteria which makes

45:31

us look at these lymph nodes. But size remains the weakest criteria for

45:35

describing a lymph node as

45:38

being

45:40

pathological or malignant. There are other criteria that are

45:44

more important and which indicate malignancy far

45:48

more strongly than size. One is necrosis.

45:51

If there is lymph node necrosis, that tells us that the lymph node is probably

45:55

malignant.

45:56

If there is calcification, not malignant, but calcified lymph nodes

46:00

can be abnormal. They could be tubercular lymph nodes or Castleman

46:04

disease, what have you.

46:07

Then, if the lymph nodes

46:10

have indistinct margins, that is a criteria for lymph nodes

46:14

to be abnormal. If they're hyperenhancing,

46:19

that's one criteria. If they show cystic change, HPV

46:23

lymph nodes, thyroid lymph nodes, these lymph nodes are often

46:26

cystic. So there are other criteria, other imaging criteria, that are more

46:30

important for calling lymph nodes

46:33

abnormal,

46:35

rather than

46:37

simply the size. So size, you can use the size

46:41

as one of the screening

46:44

sort of criteria. But you should look for other imaging

46:48

characteristics within the lymph nodes to really call them abnormal or

46:52

malignant.

46:55

Can infection mimic tumor? Of course, it can do.

46:58

But infection would have different clinical findings.

47:02

Infections progress rapidly, so the patient is going to present with fever,

47:06

other systemic symptoms.

47:08

It can definitely-- In the parotid, it's probably less common, because you

47:12

have bilateral parotitis and stuff like that.

47:14

But yeah, infections can sometimes mimic tumor, but the clinical presentation is

47:18

going to be different. Pleomorphic versus

47:22

Warthin's tumors. If there are single

47:26

lesions,

47:27

it can be difficult to differentiate the two.

47:31

Demographics is important. If you're looking at an older

47:34

person with smoking, with a history of smoking,

47:37

especially if the lesion has cystic change, then suspect Warthin's

47:41

tumor. But pleomorphic adenomas are, of course, going to be more

47:45

common.

47:46

So just by stats, you're going to see pleomorphic adenomas far more commonly.

47:50

But if they are bilateral in smokers, have cystic change, think about

47:54

Warthins.

47:56

Briefly, can you say a few specific words about role of ultrasound and biopsy?

48:02

I don't do ultrasound that much, so I can

48:06

simply tell you what I know. This is not a very

48:10

specialist opinion. Ultrasound is very important in

48:15

parotid gland and submandibular gland, of course, not in sublingual that much.

48:19

But ultrasound can sometimes tell you the internal architecture

48:23

of a lesion.

48:25

But most of all, ultrasound is important for biopsy.

48:29

Because most of these lesions will undergo cytological evaluation

48:33

because of how different

48:36

salivary gland lesions mimic each other.

48:38

Sometimes low-grade malignancies can look benign, so

48:42

cytology is always very important

48:45

in salivary gland lesions. So ultrasound is more

48:50

importantly used for guidance in FNA and

48:53

biopsy. So that's

48:55

pretty much my extent of knowledge about ultrasound.

48:58

Sorry about that.

49:00

If suspected lymphoma, will the absence of suspicious lymph node make

49:04

lymphoma unlikely? I don't think so.

49:07

You can have non-Hodgkin's lymphoma in the parotid gland

49:12

without lymph nodes elsewhere. So I would not rule that out.

49:16

If you have the typical appearance of a low T2

49:19

signal salivary gland lesion that avidly enhances, it could very well be

49:23

lymphoma without other lymph nodes elsewhere.

49:26

So it could be extranodal non-Hodgkin

49:30

lymphoma.

49:32

Difference between Waldeyer ring pathology

49:36

if involving palate.

49:39

I don't know if I understand that

49:41

question.Waldeyer ring is basically

49:46

lymphoid tissue.

49:50

The soft palate sometimes could have lymphoid tissue, but

49:55

the hard palate where lesions are more common,

49:59

salivary gland lesions are more common.

50:00

It's different from the Waldeyer ring itself.

50:04

Can we confidently call pleomorphic adenoma in parotid if it is T2 bright and well

50:08

marginated, and should we still be giving differentials?

50:12

I think if you see a very well-defined lesion that has no margin

50:16

spiculation, is T2 bright, enhances

50:20

homogenously, you can say that this is a pleomorphic adenoma.

50:24

You don't have to always hedge and say that it could be

50:28

malignant. Pleomorphic adenomas are very common in the parotid,

50:32

and if you see a homogenous T2 bright lesion,

50:35

call it a pleomorphic adenoma. It's okay.

50:40

Does the high ADC value help in differentiate

50:44

PSA from Warthin?

50:47

Do they mean pleomorphic adenoma?

50:52

I don't know what PSA is.

50:59

But

51:00

pleomorphic adenomas and Warthins usually have low ADC.

51:04

Sorry, high ADC. They both have high ADC, but I don't think I can

51:08

use diffusion

51:10

for differentiating Warthins from

51:14

pleomorphic.

51:18

The size criteria that you mentioned are the short or long axis.

51:21

So,

51:22

in the head and neck world, the size criteria that we use is

51:26

long-axis on axial CT images.

51:31

So again, the multiple

51:37

studies that have

51:39

come up with the size criteria, they have used axial

51:43

long-axis measurements as the criteria for

51:47

describing normal from abnormal lymph nodes.

51:50

Now, one thing we should remember here that, when we are screening

51:54

lymph nodes, when we are trying to say whether they're normal or abnormal, again,

51:58

size being the weakest criteria. When we know that the lymph node is

52:02

abnormal, it's a malignant lymph node, and when we are describing

52:06

lymph nodes for staging, where three centimeter and six centimeter is the criteria,

52:10

there we are not using long or short axis, we are using the maximum

52:14

size of the lymph node in whichever plane it could be.

52:17

It could be in axial plane, coronal plane, or sagittal

52:21

plane. When we are describing lymph node size for staging,

52:25

it should be the largest

52:28

dimension of that particular lymph node, and that's helpful in

52:32

staging rather than a long or a short axis.

52:38

I think that's-

52:39

I think you got them all.

52:41

Yeah.

52:42

That was great. 12 questions,

52:44

five minutes. Really good job. Thank you so much for being here.

52:47

That was an awesome lecture. Appreciate it.

52:50

Thank you. Thank you for inviting me.

52:52

Absolutely. And thank you for everyone else for participating in today's noon

52:56

conference and asking great questions.

52:59

You can access the recording of today's conference and all our previous noon

53:02

conferences by creating a free account.

53:04

We will also email out a link to this replay later today.

53:08

Be sure to join us next week on Thursday, June 18th at 12:00 PM

53:12

Eastern, where Dr. Richard Barger will deliver a lecture entitled "MSK

53:15

Ultrasound: Common Entities and Key Imaging Findings." You

53:19

can register for that at medally.com and follow us on social media for updates on

53:23

future noon conferences. Thanks again for learning with us, and have a great

53:27

day.