0:01

So this is an example of a squamous cell

0:03

carcinoma involving the floor of the mouth,

0:05

and it makes a couple of very important points.

0:08

First of all, the imaging findings

0:10

here are completely non-specific.

0:12

In fact, I remember when I looked at this case,

0:14

I thought it was gonna be a minor salivary gland cancer.

0:16

Well, the pathology came back

0:18

to be squamous cell carcinoma.

0:20

So if you do see a solid aggressive lesion in an adult

0:23

involving the floor of the mouth, just statistically,

0:26

it's gonna be squamous cell carcinoma,

0:28

um, more likely than anything else.

0:31

So when we look at the floor of the

0:32

mouth, again, anatomy is so important.

0:34

So I'm gonna go over the normal

0:36

anatomy of the floor of the mouth again.

0:38

So here is our mandible here.

0:40

This structure right here is the mylohyoid muscle.

0:43

Then we have a structure just medial to

0:45

it, which is gonna be the sublingual gland.

0:47

And here's our hyoglossus muscle.

0:50

Now if you look real closely,

0:51

there's our friend right here.

0:52

This is the genioglossus muscle

0:54

that goes from the genial tubercle

0:56

to this transverse muscle

0:57

here, which is the tongue base.

0:59

So again, hence the term genioglossus muscle.

1:02

Oftentimes I'm asked is, how do you

1:04

know when you see a mass right here?

1:06

Here's our tumor, that this is located in the

1:08

floor of the mouth and not the tongue base.

1:10

And the reason is, again, all based on

1:12

anatomy, because here is our tongue base here.

1:16

This identifies the oropharynx.

1:18

Everything anterior to this is located in the floor

1:21

of the mouth, so it's essential that you understand

1:24

the difference between these vertically oriented

1:26

stripes and these laterally oriented stripes.

1:29

So when we analyze this tumor, we can see

1:32

that this tumor is intermediate signal on T1,

1:35

it densely enhances with contrast. On T2,

1:38

we can see it's very, very high signal.

1:41

See the high signal right here?

1:43

So that's why when I actually saw this, I thought,

1:45

well, maybe this is gonna be minor salivary gland,

1:47

but remember, the T2 signal characteristics

1:50

of squamous cell carcinoma can be very variable.

1:53

So this is a squamous cell carcinoma

1:56

involving the floor of the mouth.

1:57

Now when we look at the coronal images.

1:59

I just wanna point out the normal

2:01

anatomy of that floor of the mouth.

2:03

So this muscle right here is the mylohyoid muscle.

2:07

This connects with the hyoid bone

2:09

inferiorly, and then there's another

2:10

mylohyoid muscle that comes superiorly.

2:13

So when we talked about the normal anatomy of

2:15

the floor of the mouth, I talk about the teacup.

2:17

So essentially everything within this teacup

2:20

here is located within the floor of the mouth.

2:23

So again, classical example, squamous cell

2:26

carcinoma involving the floor of the mouth.

2:29

The imaging findings, the sequences, the

2:31

signal characteristics are nonspecific.

2:33

But if you do see something like this,

2:35

number one should be squamous cell carcinoma.

2:37

Number two should be minor salivary gland carcinoma.