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This was a young adult who presented with thickening

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of the anterior wall of the external auditory canal.

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Most of the time,

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when we're dealing with skin lesions or subcutaneous

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lesions, CT scan is favored over MRI scanning.

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However, in some of these examples,

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the patient has been evaluated with the clinician, and

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they pretty much well know what's going on.

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In this case,

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they weren't exactly sure what was it that was

0:28

deforming the anterior wall of the external auditory canal.

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As we scroll in this case,

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we come up from the parotid gland.

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We see the normal external ear structures.

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The parotid gland looks pretty good.

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Here is the cartilaginous portion

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of the external auditory canal.

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Here is the bony portion of the

0:43

external auditory canal.

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And you notice that superficially associated

0:47

with the external ear,

0:48

there is a cystic structure which is predominantly

0:51

in the skin surface and extending

0:53

to the subcutaneous fat.

0:55

It's relatively round and it's in low of low density,

1:00

and then it connects to the cartilaginous

1:04

portion of the external auditory canal.

1:07

If we look at this on coronal imaging,

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you see it here that it is located in the superior

1:14

wall of the cartilaginous portion of

1:16

the external auditory canal.

1:19

If we were to see this anywhere else in the body,

1:22

a cystic lesion of potentially mixed

1:25

density with some calcification,

1:28

we would correctly identify this

1:30

as an epidermal inclusion cyst,

1:32

which is effectively a congenital lesion

1:37

that occurs anywhere in the body,

1:39

usually in the subcutaneous tissues.

1:42

And it would be similar to an epidermoid

1:46

or epidermal inclusion cyst.

1:48

The other thing that can occur in this superficial

1:52

layer would be an inflammatory lesion, associated

1:55

with either a hair follicle or even acne

2:00

that can occur and lead to inflammatory

2:03

collections in the subcutaneous fat.

2:05

Most of the epidermoids associated with the external

2:08

auditory canal are actually located within

2:11

the external auditory canal,

2:13

not in the wall of the cartilaginous portion,

2:18

as seen here.

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When the clinicians look in and they identify a

2:24

soft tissue mass in the external auditory canal,

2:27

they want to identify it as either a white lesion

2:30

or a red lesion. White lesions, by and large,

2:33

are epidermoids, white pearly lesions that

2:36

they can see in the external auditory canal.

2:39

Red lesions are your hemangiomas in the neonates or

2:45

venous vascular malformations in the older

2:48

child or young adult. So in this case,

2:51

they wouldn't be able to see it because

2:53

it's actually in the wall.

2:54

But this was effectively an epidermal inclusion

2:56

cyst, or epidermoid that was associated

3:00

with the anterior wall of the external auditory canal.