0:01

Oncocytomas are not very common lesions.

0:04

Certainly, the benign lesions of the parotid gland

0:07

are dominated by pleomorphic adenomas

0:09

and Warthin's tumors. However,

0:11

this is my one teaching file case of an oncocytoma.

0:15

And it shows relatively nicely the finding of a

0:19

vanishing tumor. So here on the T1-weighted scan,

0:22

we see the lesion very nicely,

0:25

and we're going to describe it in the superficial

0:28

portion of the parotid gland.

0:31

We don't see any malignant lymphadenopathy.

0:33

We don't see any approaching of the normal

0:36

appearance of the stylomastoid foramen.

0:40

We look at it on T2-weighted

0:41

scan and it's not lighting up the way a

0:44

pleomorphic adenoma lights up.

0:47

Therefore, we're going to recommend a biopsy.

0:49

If it lights up like a bulb,

0:51

the way pleomorphic adenoma does,

0:53

then we suggest that it's a pleomorphic adenoma

0:55

and the surgeons may go in even without doing

0:58

a biopsy. On the post-gadolinium-enhanced scan,

1:01

we have that phenomenon of the "vanishing tumor."

1:05

So although this enhances slightly more

1:07

than the normal parotid tissue,

1:09

you can see that you lose the conspicuity of the

1:12

lesion, and therefore it seems to be vanishing

1:15

from its T1 appearance.

1:18

And this is the feature that people have

1:21

described with the oncocytoma.

1:25

On the coronal post-gadolinium-enhanced scan,

1:28

we've gotten a little bit more time

1:29

for the tumor to imbibe contrast,

1:31

but nonetheless,

1:34

its contrast with the normally enhancing

1:38

parotid tissue is limited.

1:40

Hence the term "the vanishing parotid tumor"

1:44

equals oncocytoma.

Oncocytoma

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