0:00

This was a five-month-old who had a palpable

0:04

abnormality on the left side of the upper neck.

0:09

As we scroll through the sections,

0:12

you note that there is a cystic structure at

0:16

the junction between the superficial and

0:18

deep portion of the parotid gland.

0:22

When you have a cyst within the parotid gland,

0:25

you want to give contrast to see whether it

0:27

shows contrast enhancement to see whether

0:29

it's a cystic neoplasm.

0:31

Now, in a five-month-old with a cyst in the parotid gland,

0:35

the differential diagnosis is relatively limited.

0:39

Normally we would consider things such as a sialocele,

0:43

which is an outpouching of the glandular

0:47

structures of the parotid gland after trauma.

0:51

So this would be effectively like a ruptured

0:54

ductal system in which there is insistment.

0:58

You can also have a pseudocyst which may

1:02

occur within the parotid tissue that no

1:04

longer communicates with the ductal system.

1:08

HIV-related lymphoepithelial cysts will be

1:11

another consideration in a different

1:13

age group. In a five-month-old,

1:15

we usually do not think about HIV infection.

1:19

So there's a number of various cysts.

1:21

We've talked about neoplasm,

1:22

cystic neoplasms, which mucoepidermoid would

1:25

probably be the most common in a child.

1:27

We talked about traumatic cysts,

1:29

we talked about developmental cysts with a

1:32

sialocele, and we also talked about infectious cysts.

1:36

However, obviously in a five-month-old we have to

1:39

think about a congenital cyst first and

1:44

child has undergone trauma, et cetera, or an infection.

1:49

So the first branchial cleft cyst is a cyst

1:53

which occurs in association with the

1:59

And here we are able to identify the

2:01

mandible and this is just retromandibular

2:04

in association with the parotid gland.

2:07

So in the classification of first

2:12

different varieties of classification.

2:14

One is the Arno classification, which I mentioned,

2:17

which is associated with where the cyst is

2:21

in relationship to the parotid gland and the mandible.

2:24

And then there is also the work classification.

2:28

The work classification specifies that

2:33

work type II, first bronchial cleft cyst may

2:37

show a fistula to the external auditory canal.

2:41

So it behooves us to look at the shape of

2:44

this cyst and determine whether or not it

2:47

could be extending to the external

2:49

auditory canal. And for that, I want to show you

2:53

what this cyst looks like on the sagittal and the coronal

2:57

images. So I'll use my magic pen and make sure that

3:02

everyone sees what we're talking about,

3:04

which is this cystic structure,

3:06

which actually has a fairly well-defined

3:09

border associated with it.

3:11

And this corresponds to this lesion on the sagittal scan

3:16

with, if you will, a trailing edge which is heading superiorly

3:23

to the external canal. On the coronal scan,

3:26

we have the same, it's almost teardrop,

3:28

if you will,

3:29

but it has a little triangular tip to it,

3:33

which is heading to the external auditory canal.

3:36

Let's look at the external auditory canal in this coronal view.

3:40

And here you see the external auditory

3:43

canal and the proximity of this upper

3:46

portion of the cyst to the external auditory canal.

3:50

So we will look for clinically a fistula or

3:54

a dimple in the external auditory canal

3:56

inferior wall that may show a communication

4:00

with this cyst. And trailing this upward

4:05

towards the external auditory canal,

4:09

you see this unusual shape to this cyst

4:13

which extends right up to that external

4:16

auditory canal and has a small component

4:19

associated with it, right at the external auditory canal.

4:23

So this would be our work type II,

4:28

first branchial cleft cyst with a fistula to the

4:34

external auditory canal.