0:01

Let's contrast the last case of a parapharyngeal

0:04

space pleomorphic adenoma with this lesion.

0:08

This was a lesion that was discovered based on the

0:11

appearance of a submucosal mass in the nasopharynx

0:15

on the right side. So, on the T1-weighted scan,

0:18

we see the mass pretty readily here,

0:21

and we can see that the nasopharyngeal soft tissues

0:24

are displaced from the right side to the left side.

0:28

Once again, we have the question,

0:30

is this a deep lobe parotid mass or is this

0:34

a parapharyngeal space mass? And again,

0:37

this can be tricky. Why is this important?

0:40

Most of the time with parapharyngeal space masses,

0:43

the approach is underneath with

0:45

a transcervical approach,

0:47

and there is less concern about the facial nerve.

0:51

If you are dealing with a deep lobe parotid mass,

0:55

you're more concerned about the facial nerve.

0:57

And often there is a dissection which is made

1:00

superficially from a superficial skin incision over

1:03

the parotid gland and possibly through a transcervical

1:07

approach as well. In this case,

1:10

what we see is that the parapharyngeal space fat is

1:14

being predominantly displaced medially and anteriorly.

1:19

Medial and anterior displacement of the parapharyngeal

1:22

space fat indicates a deep lobe parotid mass.

1:26

Now, I would have a little bit of hesitation because I do

1:30

see some bright signal intensity around

1:31

the periphery of this mass,

1:33

raising the possibility,

1:34

'Is it primarily in the parapharyngeal space fat?' However,

1:38

the appearance of this fat being displaced anterior

1:42

medially, more likely suggests that this is coming

1:45

off of the deep portion of the parotid gland

1:49

rather than being a primary

1:52

parapharyngeal space mass lesion.

1:56

Now that we've discovered and determined

1:59

where we think it's arising from,

2:00

we can take a look at the T2-weighted imaging and

2:03

see that this is a very bright lesion

2:06

on T2-weighted scanning,

2:07

suggesting that it is a benign mass,

2:09

a pleomorphic adenoma. Now, it's quite large in size,

2:13

and therefore,

2:14

we have a little bit of concern about

2:16

what's going to happen at surgery,

2:18

particularly with regard to the potential for

2:20

facial nerve injury as they dissect it,

2:24

as well as the removal. And with contrast enhancement,

2:28

we also see that the lesion is fairly well defined,

2:31

albeit with some heterogeneity to the enhancement

2:37

on the T1 post-gad scans.

2:41

I just want to go back to the T2-weighted scans

2:44

and mention a couple of things, and that is,

2:46

what do we do about these guys?

2:48

So here in the right parotid gland,

2:51

we see three separate lesions.

2:54

Sometimes you'll see only one of them like this here.

2:58

What to do about these?

3:00

Could these be additional pleomorphic adenomas?

3:03

Is this metastatic disease in the parotid gland?

3:07

Well, when they are kidney bean-shaped

3:10

and have well-defined borders,

3:12

I ascribe these to intraparotid lymph nodes.

3:15

The parotid gland is the only salivary gland that has

3:21

late encapsulation with lymphoid tissue within it.

3:25

That's the reason why you can get

3:27

lymphomas of the parotid gland,

3:28

but you don't get lymphoma of the submandibular

3:30

gland or sublingual gland. And similarly,

3:32

you can get intraparotid lymph nodes in the

3:35

parotid gland because it has late encapsulation

3:38

and does have lymphoid tissue.

3:40

So in this situation where you have multiple, small,

3:45

kind of oblong-shaped lesions that

3:47

have well-defined borders,

3:49

and sometimes you will see some lymph nodes

3:51

outside of the parotid gland adjacent to it,

3:55

like these lymph nodes here.

3:58

In that situation,

3:59

I will just dismiss these as intraparotid lymph nodes.

4:04

Could you have a single small pleomorphic adenoma

4:10

that you mistake for a lymph node?

4:12

Absolutely. That's a potential pitfall.

4:15

But when you have multiple ones,

4:18

they look like they have well-defined borders.

4:20

You have lymph nodes bilaterally, more likely to

4:22

suggest that this is benign lymphadenopathy.