0:02

One of the more unusual benign neoplasms

0:05

of the parotid gland.

0:06

And again, this is a tumor-like Warthin's tumor that

0:10

predominates in the parotid gland,

0:12

is the oncocytoma.

0:14

This is a tumor which, like Warthin's tumor,

0:16

tends to occur in older individuals.

0:19

And this is a tumor that, like Warthin's tumor,

0:23

may accumulate pertechnetate

0:27

on your technetium scan.

0:29

They have been referred to as the vanishing tumor,

0:34

in that with contrast,

0:36

they tend to become iso-intense to the

0:38

normal enhancing parotid tissue.

0:41

They usually are not quite as bright as what

0:44

you see on the pleomorphic adenoma

0:47

T2-weighted imaging.

0:50

Here is a patient who had an oncocytoma.

0:54

You see that, like most benign tumors,

0:56

it shows a relatively well-defined border.

1:02

So quickly, we'll ask the question: is this from the

1:04

parotid gland or is this from the parapharyngeal space?

1:08

What we see is that this is invaginating

1:10

into the parapharyngeal space fat,

1:12

and since I told you it was an oncocytoma and

1:16

that they are relatively exclusively

1:18

seen in the parotid gland,

1:20

you should know that this is a lesion which is

1:23

going from the superficial portion of the parotid

1:25

gland to the deep portion of the parotid gland,

1:27

then invaginating into the parapharyngeal space.

1:30

So this is a patient with an oncocytoma.

1:36

This is a case from the literature,

1:37

a recent article in the American Journal of Neuroradiology,

1:41

referring to the vanishing nature of the mass.

1:45

So this is what's called oncocytoma, the vanishing

1:48

parotid mass. What do we mean by vanishing?

1:52

Well, it's very well seen on the T1-weighted scan.

1:56

And remember I said, we go to the T1-weighted

1:57

scan to detect the abnormality in

2:00

the salivary gland tissue,

2:01

particularly the parotid gland,

2:03

which is brightish on T1-weighted scan.

2:06

You notice on the T2-weighted scan,

2:07

it's low in signal intensity and vanishing right

2:11

almost iso-intense to the normal

2:15

parotid tissue around it.

2:18

And after the administration of gadolinium,

2:21

again, it simulates that of the normal

2:24

parotid tissue does the tumor.

2:27

So this is why it was referred to

2:28

as the vanishing parotid mass.

2:31

Remember that as opposed to pleomorphic adenomas,

2:34

which will enhance more than the parotid tissue

2:37

and tends to imbibe more and more

2:39

contrast with delayed imaging.

2:41

So this is again a nice example

2:44

from the article by Dr. Patel on oncocytomas.

2:50

Oncocytomas are somewhat heterogeneous.

2:54

However, this was a case of an oncocytoma

2:57

that was demonstrated on

3:00

T1, T2 and post-gadolinium-enhanced scan,

3:02

where it was enhancing more than the parotid tumor...

3:06

the parotid tissue.