0:00

This was an 89-year-old patient who presented with

0:03

a soft tissue mass in the left external auditory

0:07

canal. Here, on the bone windows,

0:09

we see the mass that involves the

0:13

bony external auditory canal.

0:15

The cartilaginous portion looks pretty good.

0:19

And as we evaluate the left side,

0:23

we may want to take a quick moment to compare with

0:26

the right side to see whether we feel that the

0:29

external auditory canal is expanded or not.

0:32

And by my judgment,

0:34

it looks like this indeed is not.

0:38

An expanded external auditory canal.

0:40

Looks fairly symmetric with the contralateral side.

0:44

So once again,

0:45

we have a mass that is hard to get more specific in

0:50

characterization without having some

0:53

clinical information. In this case,

0:55

the patient's lesion was bland in color.

0:58

It was not white. It was not red.

1:00

It was kind of a fleshy abnormality.

1:03

And the only other history that you could gather

1:06

from the electronic medical record was that the

1:09

patient did have recurrent episodes of sinusitis.

1:12

So we have just a tiny little bit of the sphenoid

1:16

sinus here showing that there is some inflammation

1:20

that is present in the left sphenoid

1:22

sinus compared to the right.

1:25

So with this information,

1:27

we might want to get additional imaging.

1:30

You could do a contrast-enhanced study to see

1:32

whether this is an enhancing mass or

1:35

you can better characterize it,

1:36

particularly if you're considering the idea of

1:39

cholesteatoma by performing an MRI scan.

1:42

In this case, the patient did have an MRI scan.

1:45

I'm going to pull down the post-gad

1:47

T1-weighted scan first.

1:49

What we notice on the post-gad T1-weighted scan is that

1:52

the lesion is present as a lower signal intensity on

1:57

T1, but does not show any contrast enhancement.

2:01

That's reassuring that we're not dealing with

2:04

a vascular lesion or a vascular neoplasm.

2:08

That would be something that could lead to problems

2:12

at the time of surgical intervention.

2:15

The next thing that we might want to do is to look

2:17

at our diffusion-weighted imaging and T2-weighted

2:21

scan. So on the T2-weighted scan,

2:23

we see that this mass is slightly bright in signal

2:26

intensity. It's not fluid completely.

2:30

In other words,

2:31

the signal intensity does not simulate CSF.

2:34

It's kind of intermediate in signal intensity.

2:37

The next thing to look at, as I mentioned,

2:39

was the diffusion-weighted imaging.

2:42

And on the diffusion-weighted scan,

2:47

you can see that this lesion is slightly

2:49

bright in signal intensity

2:52

and on the ADC map corresponds to a darker area.

2:57

Well, that's very helpful in that.

3:00

The entity that is typically associated with bright

3:04

signal intensity on diffusion-weighted imaging

3:07

associated with restricted diffusion

3:09

is the cholesteatoma,

3:11

and that may be a congenital cholesteatoma

3:15

or it may be an acquired cholesteatoma,

3:17

both of which are usually bright on the DWI.

3:21

The absence of contrast enhancement also

3:24

is consistent with a cholesteatoma.

3:27

I will say that for the evaluation of the temporal

3:30

bone lesions with diffusion-weighted imaging,

3:34

you may want to switch to a spine echo or fast spine

3:38

echo type of DWI sequence as opposed to the gradient

3:41

echo type of epicequence because of the potential

3:46

for having an artifact that obscures detail.

3:49

In this case, it was a good quality scan,

3:51

where indeed it represents a lesion

3:54

that shows restriction.

3:56

So the combination of the diffusion-weighted MRI

3:59

scan and the post-contrast MRI scan with the CT scan

4:04

would suggest a diagnosis of cholesteatoma in

4:07

this patient. And this particular patient did

4:12

go on to have an ear canal surgery to remove

4:16

the cholesteatoma.