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This patient was a seven-year-old child who

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presented with fullness in the right side of the

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face adjacent to the external ear. On the axial

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scans, as we scroll through the neck,

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we come into a cystic area which

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is associated with the parotid gland.

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It has some edema that is extending to the

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subcutaneous fat and it extends superficially with

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some edema even to the skin surface around the

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posterior portion of the pinna of the ear.

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As you can see,

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it seems a little bit multiloculated.

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There's a component here and here.

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Let me mark that for you.

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So, there's one component,

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which is here, and then there's another

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component here. And as we scroll up,

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you'll see that there's also a little more

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superficial component just behind

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the external ear.

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So let's continue to scroll and just keep

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your eyes on the anatomy there.

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And you can see there's some edema which is

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extending superficial to the main component

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of this abnormality. And then even higher,

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we have this low density which extends to the

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external auditory canal posterior wall.

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And you see that it encroaches on that

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posterior wall of the external auditory canal.

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On our coronal images,

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we see a similar phenomenon, and that is a

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multiloculated cyst which is associated with the

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parotid gland, but also extends to the walls

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of the external auditory canal.

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And here you can see that low-density area of the

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cyst. So what's in our differential diagnosis?

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Firstly, in a seven-year-old,

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I would be concerned about a complication of parotitis.

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Parotitis is an inflammation of the parotid gland.

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You can have abscesses within the parotid gland,

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and the way this is multiloculated irregular

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associated with some edema in the subcutaneous fat,

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would suggest that it may be a cellulitis

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with parotid abscess.

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And you want to express the parotid gland and see

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whether purulent material comes

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out of the parotid duct,

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which the parotid duct you're seeing right

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here inserting in the buccal mucosa.

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So clinically, that might be what one would expect to see.

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The differential diagnosis would also include

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something related to mastoiditis.

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So we sometimes talk about the bezold abscess,

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which is at the mastoid tip.

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Here's our mastoid tip.

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We have this low density just

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adjacent to the mastoid tip.

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So this could be mastoiditis with bezold abscess.

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I think that you can see even on this

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soft tissue window that there is no opacification

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of the mastoid air cells.

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So it's unlikely that there's an infection

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in here that is leading to a

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flocculated fluid collection associated

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with the mastoiditis.

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So once you identify that there is this potential

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communication with the external auditory

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canal on axial and coronal scanning,

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it shifts from the inflammatory cystic lesions

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to a more likely congenital lesion.

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Now, that congenital lesion,

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that first branchial cleft cyst with

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fistula could be superinfected,

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which could account for the cellulitis and the

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multiloculated irregular appearance to it,

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because most first branchial cleft cysts are

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unilocular or not multiloculated.

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So I would have concluded that in the

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absence of the mastoiditis,

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in the absence of purulent material

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coming out of the parotid duct, that most likely

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represents a superinfected first branchial cleft

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cyst and fistula to the external auditoy canal

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and recommend evaluation of the external auditory

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canal for a potential opening in that location.

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As far as the classification,

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if we have that fistula, that would be the work

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type 2 classification of first branchial cleft cyst.

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By virtue of this being in the parotid gland,

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as opposed to in the upper cervical region,

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this would represent the Arno Type 1 intra-parotid

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first branchial cleft cyst, as opposed to the upper

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cervical Arno Type 2 first branchial cleft cyst.