0:00

Benign masses that occur in the external auditory

0:03

canal are plentiful.

0:05

The most common, far and away, is going

0:07

to be cerumen impaction,

0:09

or what some people would call

0:11

"cotton swab syndrome."

0:13

This is because those individuals who are avid

0:16

users of cotton swabs sometimes will just push

0:19

that earwax further in towards the tympanic

0:22

membrane and lead to cerumen impaction.

0:26

The bony abnormalities that can occur in the

0:28

external auditory canal are exostoses and osteomas,

0:32

and distinguishing between them,

0:34

sometimes, is difficult.

0:36

We usually say that if it's a diffuse

0:38

process that may be bilateral,

0:39

we're going to call it exostoses;

0:41

whereas, if it's a single unilateral abnormality,

0:45

we would call it an osteoma.

0:47

The soft tissue abnormalities in the external

0:51

auditory canal that are mass-like include

0:53

keratosis obturans,

0:55

which is a plug of tissue that may lead

0:59

to a painful external auditory canal.

1:03

It may be associated with bronchiectasis

1:06

and chronic sinusitis.

1:07

It's almost like a ciliary motility

1:10

disorder that may be bilateral.

1:12

Cholesteatomas are of two varieties: the congenital

1:16

cholesteatomas, which we call epidermoids;

1:18

and the acquired cholesteatomas,

1:20

which may be an inflammatory process.

1:23

And those also are associated with either

1:26

external auditory canal stenosis or sometimes atresia.

1:31

The red lesions are the hemangiomas

1:34

and venous vascular malformations.

1:38

Here we have a patient who has soft tissue in the

1:42

bony portion of the external auditory canal,

1:45

and it looks like it's likely going to be

1:47

displacing the tympanic membrane inward.

1:49

Well, what could this be?

1:51

There's any number of things that this may be.

1:53

As I described previously,

1:55

if you see a low-density border with the external

2:00

auditory canal in the periphery of the mass,

2:02

we're more likely to suggest that it represents

2:04

cerumen. If it's of low density,

2:07

it's more likely to represent cerumen.

2:09

However,

2:09

if it's a soft tissue mass that doesn't

2:11

have that characteristic feature,

2:13

we really have to rely on the electronic medical

2:16

record to identify whether this is a white mass or

2:20

a blue mass or a red mass for

2:22

our differential diagnosis.

2:26

Cholesterol granuloma is the purplish-blue mass

2:30

that can occur in the external auditory canal.

2:34

It may be blood products that we are seeing more

2:38

on the venous side than the red mass

2:41

which are usually venous

2:42

vascular malformations.

2:45

These may or may not have bony

2:47

defects associated with them,

2:49

but it's sort of that blue-domed cyst that we

2:53

also have heard about in the Petrous apex.

2:57

So, a cholesterol granuloma. These

3:00

are usually bright on T1 and bright on T2

3:02

because they represent blood products in the

3:05

external auditory canal or Petrous apex.

3:08

The cholesteatoma,

3:10

as I referred to, is of the inflammatory variety,

3:15

is ingrowth of squamous epithelium that may be

3:18

secondary to trauma or infection or previous

3:21

surgery, and is less commonly found in the external

3:25

auditory canal than it is in

3:27

the middle ear cavity.

3:29

And this is usually seen as a soft tissue mass

3:33

that is associated with bony erosion.

3:36

This may be distinguished from the keratosis

3:39

obtusans because with keratosis obturans, usually,

3:43

the external auditory canal is expanded without

3:48

the same focal bony erosion.

3:54

So, keratosis obturans represents accumulation

3:57

of desquamated keratin.

3:59

It is more common than acquired cholesteatoma

4:02

or congenital cholesteatoma of the external

4:04

auditory canal. As I mentioned,

4:05

it may be bilateral and associated with chronic

4:08

sinusitis or bronchiectasis, and it's a painful

4:11

process within the external auditory canal.

4:13

So, usually, we see expansion of the external

4:16

auditory canal more so than a focal erosion, and

4:20

that also will help us in our differential

4:23

diagnosis with cholesteatoma.

4:27

Here we have a patient who has a soft tissue mass

4:31

that is opacifying the cartilaginous, as well as

4:36

bony portion of the external auditory canal.

4:39

As we look at it on the coronal image, we note that

4:43

there appears to be some widening of the external

4:47

auditory canal, and this is of a more benign

4:52

appearance. It's not really aggressive erosion;

4:56

it's just a little bit of remodeling of the

4:59

soft tissue in the external auditory canal.

5:03

So, with that bony remodeling,

5:05

we'd be more likely to suggest that this represents

5:08

a benign process, either a neoplasm or

5:11

in the differential diagnosis would

5:12

be keratosis obturans.

5:15

If this is a soft tissue mass that

5:18

has a pale appearance to it,

5:21

we're more likely to suggest that this represents

5:23

an epidermoid, that congenital cholesteatoma.

5:27

Whereas if what the clinician

5:29

is seeing is a red mass,

5:30

we're going to suggest it represents

5:32

a venous vascular malformation.

5:34

If it represents a purplish-blue mass,

5:37

we're going to suggest that it could

5:39

represent a cholesterol granuloma.

5:43

Here are a few more examples in this collage of

5:46

various soft tissue masses in

5:48

the external auditory canal.

5:51

On the far-left image, we see that soft tissue

5:55

which is extending in the bony and cartilaginous

5:59

portion of the external

6:00

auditory canal, and this was associated with an

6:03

inflammatory process, and this was an acquired

6:06

cholesteatoma. The acquired cholesteatoma

6:09

like the congenital cholesteatoma

6:10

is usually a white lesion.

6:12

The keratosis obturans case is a little bit

6:16

atypical in that usually we don't

6:18

see as much focal erosion.

6:20

We see more of an expansion of the external auditory

6:23

canal, which you see also present

6:25

in this individual.

6:27

And this increased width of the external auditory canal

6:31

is one of the findings that would suggest

6:34

keratosis obturans, as opposed

6:36

to an acquired cholesteatoma

6:41

which usually erodes the bone before it

6:43

expands the external auditory canal.

6:45

This last case on the right-hand side,

6:48

as you can see,

6:49

would be something that was protruding

6:50

into the external auditory canal.

6:53

In this case, it was blue at otoscopy and did

6:56

indeed represent a cholesterol granuloma.

6:59

The cholesterol granuloma may be on an

7:01

inflammatory or traumatic basis.

7:03

It may be a foreign body reaction

7:04

to something that was

7:08

within the external auditory canal,

7:11

either from something like an insect bite

7:14

or a portion of a stinger in the ear,

7:18

if there was a bee sting, for example.

7:19

So, something that should not be in the

7:23

external auditory canal, eliciting this hemorrhage and

7:27

inflammatory process, known

7:30

as a cholesterol granuloma.