0:00

It's a little bit curious how you get

0:02

squamous cell carcinoma in the parotid gland.

0:05

The parotid gland should have

0:08

salivary gland epithelium.

0:11

And squamous epithelium is unusual

0:14

in the parotid gland.

0:15

It may line the parotid ducts in the...

0:20

with squamous metaplasia

0:22

that may occur in the parotid duct.

0:25

So whenever you see the histology

0:27

of squamous cell carcinoma,

0:28

you have to be a little bit suspect.

0:30

And what are you suspicious of?

0:32

You're suspicious of whether or not this could

0:35

represent a lymph node that has metastasized

0:39

to the parotid gland,

0:40

and it's a squamous cell carcinoma of the lung,

0:43

or squamous cell carcinoma of the skin.

0:45

Particularly if you have a dermal lesion that

0:48

looks like it may be infiltrating

0:50

the parotid gland,

0:50

then they could mistake squamous cell carcinoma

0:53

of the skin infiltrating the parotid gland

0:56

for a primary parotid process.

1:00

These lesions, again, have relatively dark signal

1:03

intensity on T2-weighted imaging,

1:06

and they may show early involvement

1:09

of the 7th cranial nerve.

1:12

Here is a patient who had a primary parotid

1:16

squamous cell carcinoma, which demonstrated

1:20

spread into the stylomastoid foramen.

1:24

And on the post gadolinium T1-weighted scan,

1:27

you see a very thick descending portion of the

1:31

7th cranial nerve exiting the stylomastoid foramen.

1:35

So this was a primary parotid squamous cell

1:38

carcinoma with perineural spread

1:40

up the 7th cranial nerve.

1:44

Here was a very curious case of a patient who

1:48

had a mass in the parotid gland that was

1:51

very heterogeneous and angry looking.

1:54

This is a T2-weighted scan where it's

1:56

quite dark on a T2-weighted scan.

1:58

This was biopsied and it was indeed a very large

2:02

lymph node with squamous cell carcinoma

2:05

that they were able to diagnose.

2:07

And for whatever reason,

2:08

this patient's primary tumor was on the penis.

2:13

And so it was skin cancer from the penis,

2:16

metastatic to the parotid gland.

2:18

You're not going to see too many of them.

2:22

Remember that the parotid gland is the one that has

2:25

the potential for having lymphadenopathy within it

2:28

because of its late encapsulation

2:31

with lymphoid tissue.

2:33

However, those lymph nodes are usually draining

2:36

skin cancers from around the face,

2:40

rather than, obviously, from the perineal region.

2:43

That lymphoid tissue also accounts for

2:46

lymphoepithelial lesions that can occur in AIDS

2:50

and for cystadenoma lymphomatosum

2:53

that occurs in Warthin's tumor.