0:01

There are some areas of anatomy that I really

0:04

enjoy, and salivary glands are part of the anatomy

0:10

and pathology that is quite refreshing in

0:12

neuroradiology and head-neck imaging.

0:15

And I like the Salivary glands because they have

0:17

a wide variety of both benign

0:19

and malignant neoplasms.

0:21

If you do something like the carotid space,

0:24

basically, the carotid space is dominated 95% of the

0:27

time by benign tumors, those being

0:30

schwannomas and paragangliomas.

0:32

But with salivary gland imaging, you have a wide

0:35

variety of neoplasms and the rate at which

0:39

there is cancer versus benign tumor.

0:42

Malignancies versus benign tumors varies

0:45

from one gland to the other.

0:47

We're going to start off talking about

0:48

the benign neoplasms first.

0:55

Now we have an 80% rule that we talk about with

0:59

regard to salivary gland pathology, and that is

1:02

that 80% of salivary gland tumors

1:05

occur in the parotid gland.

1:09

We say that 80% of parotid

1:12

gland tumors are benign.

1:17

80% of the benign tumors are pleomorphic adenomas.

1:23

And 80% of pleomorphic adenomas do

1:26

Does not show malignant degeneration.

1:33

80% overall of salivary gland tumors are benign.

1:38

So?

1:40

This is the 80% rule.

1:44

What does this mean?

1:45

This means that there are tumors that occur

1:48

outside the parotid gland in the sublingual glands,

1:51

and the submandibular glands, but

1:53

they're pretty uncommon.

1:57

One thing that I will point out is that the 80%

2:01

benign rule generally refers to parotid tumors.

2:05

Elsewhere, there is a higher rate of malignancy.

2:09

So?

2:11

Beware of that.

2:15

Jatin Shaw wrote a really beautiful

2:18

book called Head Neck Surgery.

2:22

This is from the second edition.

2:23

I think he's up to like the fifth edition.

2:25

So this was way back in 1996, but the numbers

2:28

really haven't changed that much.

2:30

This is looking at malignancy, I'm sorry,

2:34

neoplasms of the salivary glands,

2:38

of the major salivary glands, and you can see that

2:41

the vast majority of them are located in the

2:44

parotid gland, followed by the submandibular

2:47

gland, followed by minor salivary glands.

2:51

And these submandibular gland,

2:52

Sublingual gland often are combined together.

2:58

This is a very port.

3:00

Slide.

3:01

This is again from Jatin Shaw's book, and it looks.

3:05

At the rate at which you have benign.

3:09

Versus malignant tumors.

3:10

Remember that we said the 80% rule was that.

3:14

In the parotid gland, 80% are benign.

3:17

Here in Jatin Shaw's experience at the.

3:19

Memorial Stone Kettering Institute.

3:22

It was 75% benign and only 25% malignant.

3:27

80% rule applies in general.

3:31

Obviously, at Memorial Slung Kettering.

3:33

They tend to get referrals for more.

3:35

Malignancies to Slung Kettering.

3:40

Minor Salivary gland tumors.

3:43

You can see are dominated by malignancies.

3:48

So if we think of 80% rule of the Memorial.

3:51

Sloan Kettering experience.

3:53

They would say that 80% of minor salivary.

3:57

Gland tumors are malignant.

4:01

When you look at the sum mandibular and sublingual.

4:03

Glandular tissue, the rate is about 50% 50 50.

4:09

This leads to the adage that the larger the gland.

4:15

The higher the rate of benign tumors.

4:17

So the minor salivary gland tissue that's.

4:21

Microscopic, almost submilli.

4:24

So, the larger the gland, for example,

4:27

the parotid gland, 80% benign.

4:31

Then we go to sublingual and submandibular

4:33

glands, about 50% benign.

4:36

But when we go to the minor salivary gland,

4:38

only about 20% benign. The larger the gland,

4:42

the higher the rate of benign tumors.

4:44

The smaller the gland,

4:46

the higher the rate of malignant tumors.

4:52

Let's start with the parotid gland.

4:55

The parotid gland 80% rule says that 80% of

4:59

the parotid gland neoplasms are benign.

5:03

And of the benign neoplasms of the parotid gland,

5:07

80% are pleomorphic adenomas.

5:10

If you do a simple calculation,

5:12

you'd figure out that 64% (80% times 80%) of parotid

5:18

gland tumors are pleomorphic adenomas.

5:24

Hemangiomas.

5:26

And by these, I mean the congenital hemangiomas or

5:29

the infantile hemangiomas that occur in the parotid

5:34

gland as probably the second most

5:36

common of the benign neoplasms.

5:39

But they are occurring in children

5:41

and they may involute.

5:45

This is different than the venous vascular

5:48

malformation, which we don't consider a neoplasm.

5:50

We're talking about the true neoplasms,

5:53

the hemangiomas that have a growth

5:55

phase and an involution phase

5:59

in adults.

6:00

The second most common parotid gland benign

6:02

neoplasm is the Wharton's tumor.

6:04

And I warned you about Wharfin's

6:06

tumor versus Wharton's duct.

6:09

And then we have the less common oncocytomas,

6:13

schwannomas, and lipomas. I'm not listing here.

6:16

Monomorphic adenomas.

6:18

Those are also benign neoplasms, and

6:22

I'll show some examples of them.

6:29

Let's move to pleomorphic adenomas.

6:32

Pleomorphic adenomas are the most common

6:34

benign salivary gland tumor.

6:37

They are the most common benign parotid tumor.

6:41

They are the most common benign

6:43

submandibular tumor.

6:45

They are the most common benign sublingual tumor

6:49

and they are the most common benign

6:51

minor salivary gland tumor.

6:52

So, pleomorphic adenomas dominate the benign tumors

6:56

in all of the different types of salivary gland.

7:01

By and large,

7:02

the pleomorphic adenomas are sort of the

7:04

meningiomas of the brain in that demographically.

7:08

They occur in relatively young women, 30 to

7:11

50 years old, and women more so than men.

7:15

Usually two to one,

7:17

maybe two and a half to one ratio.

7:21

Their imaging feature, which is characteristic,

7:23

is that they are bright on T2-weighted imaging.

7:27

And that's what we look for.

7:29

Bright signal on T2-weighted imaging.

7:31

However, they may have calcification,

7:33

they may have fat, they may have cysts within them.

7:36

So there is some heterogeneity

7:39

to the pleomorphic adenoma,

7:41

not as much as what we see with Wharton's tumors.