0:01

All right,

0:01

so we've made it through anatomy and the benign

0:04

neoplasms it's come to we have to come to the downer

0:07

which is malignant neoplasms but there are a wide

0:11

variety of malignant neoplasms that will affect the

0:13

salivary gland. So it's actually quite exciting.

0:16

Here are the parotid malignancies

0:20

that occur and as you can see the most common

0:24

is going to be mucoepidermoid carcinoma.

0:27

Next most common is probably adenoid cystic

0:30

carcinoma and then the rest of them the acinic cell,

0:33

the adenocarcinoma,

0:34

the malignant mixed or carcinoma x pleomorphic

0:36

adenoma account for only about 10% and then

0:42

you have the lymphoma and metastases.

0:44

These are going to be the lymphoid tumors

0:47

that can affect the parotid space.

0:50

As I mentioned,

0:51

low grade mucoepidermoid carcinoma is actually

0:54

a relatively benign tumor to have.

0:57

When it gets higher grade obviously it's

1:00

more likely to have metastases.

1:02

Here we have the diagram of the different

1:05

histologies of salivary gland tumors of the parotid

1:09

gland, the submandibular gland, and

1:11

the minor salivary glands.

1:13

Within this, you can see that there is a dominance of

1:18

mucoepidermoid carcinoma in the parotid gland, but this

1:21

accounts for much less in the submandibular

1:23

and minor salivary glands.

1:25

In these glands, we have this intermediate bluish

1:28

shade which is the adenoid cystic carcinoma which

1:32

can occur more commonly in submandibular

1:35

and minor salivary gland tissue.

1:38

Here is a different reference looking at the various

1:42

types of tumors that abound in the parotid,

1:46

submandibular, and minor salivary glands.

1:49

So again, we're going to look for mucoepidermoid in

1:52

40% adenoid cystic and adenocarcinoma 15% in the

1:57

parotid gland, but the adenoid cystic carcinoma is more

2:00

dominant in submandibular and minor salivary glands.

2:05

Just to refresh your memory,

2:07

the larger the salivary gland, the higher

2:12

the rate of benign tumors.

2:15

So the parotid glands, the largest gland, have

2:17

about an 80% rate of benign tumors, the submandibular

2:21

sublingual glands about 50-50, and the minor

2:25

salivary glands dominated by malignancy.

2:28

So the smaller the gland, the higher the

2:31

rate of malignant tumors.

2:34

When we find salivary gland malignancies, we use the

2:40

T staging characteristics to identify the prognosis

2:45

and potential treatment of the salivary gland mass.

2:49

So as you can see, we are usually measuring the

2:52

lesions 2 cm or less T1-2, 2-4 T,

2:56

two greater than 4-3 if there is spread.

3:00

Outside the capsule of the salivary gland, it becomes

3:04

T3. Then T4 is invasion of the skin,

3:08

the bone, the facial nerve.

3:11

T4b, which is relatively unresectable.

3:14

Disease affects the skull base,

3:16

the pterygoid plates or with encasement

3:19

of the carotid artery.

3:22

Mucoepidermoid carcinoma is the most common of the

3:25

parotid cancers but not in the sublingual gland and

3:28

not in the submandibular gland and

3:30

not in the minor salivary glands.

3:32

It accounts for just a smaller percentage of all

3:36

parotid masses but the most common

3:39

among parotid malignancies.

3:41

Its T2-weighted signal intensity will vary

3:44

according to the grade of the tumor.