0:01

So this is a very interesting case, and again,

0:03

demonstrates the practical nature of imaging to

0:06

try to identify the specific disease entity that

0:09

we refer to as an unknown primary carcinoma.

0:12

So if you look at the bottom left-hand

0:13

corner, this was a patient that presented

0:15

with a right-sided neck mass, and oftentimes,

0:18

these patients self-identify themselves because

0:21

they'll feel a mass in the neck while they're

0:22

shaving, or someone just may notice it incidentally.

0:26

And we can see here that there is this large

0:28

mass involving the right side of the neck,

0:30

which is due to an enlarged lymph node.

0:32

So once this lymph node is biopsied, that

0:34

comes back squamous cell carcinoma.

0:36

So the challenge that we have from an

0:38

imaging standpoint is to try to identify

0:41

where the primary site of this tumor is, because

0:44

lymph nodes drain every part of the body.

0:47

So basically, the lymph nodes are connected by

0:49

lymphatics to every single part of our body.

0:51

So if we have a cancer, they drain to the lymph nodes.

0:54

So we, in a way, have to backtrack

0:57

to see where this tumor came from.

0:59

So if you look at the image on the top left-hand

1:01

corner, we can see this enlarged lymph node.

1:04

And when we see an enlarged lymph node,

1:06

there's some tricks that we can use.

1:08

If we have an enlarged level II lymph node, as

1:10

is seen here, this tells us the tumor should be

1:13

on the ipsilateral side, and they typically arise

1:16

from four main areas: the nasopharynx, the

1:18

tongue base, the piriform sinus, or the tonsil.

1:23

Those are the four areas that we look at.

1:25

Now, when you start looking to

1:27

identify the unknown primaries,

1:29

one subtle way to do it is look at the airway.

1:31

In general, the airway tends to be symmetric,

1:34

but on the other hand, if I know that there's

1:35

a metastatic lymph node on the ipsilateral

1:37

side, when I look at the airway, I can see

1:40

it's a little bit pinched off right here.

1:42

And I almost get the impression that there is

1:44

a mass right here involving the right tonsil.

1:47

Now, can you be a hundred percent sure?

1:48

Absolutely not.

1:50

But when the patient does have an unknown

1:52

primary, our job is to try to help our ENT

1:55

surgeons to perform biopsies that are at the

1:59

highest likelihood of identifying the tumor.

2:01

So this would be one area that

2:03

I'd be most concerned about.

2:05

In the United States, a majority of patients

2:07

end up undergoing a PET/CT scan, and when we

2:09

do do the PET/CT scan, we can see the robust

2:12

uptake here involving the level II lymph node.

2:15

But when we perform the PET/CT, we can see

2:18

this focal area of uptake involving the right

2:20

tonsil on the axial images, and also on the

2:24

coronal images, which correlates with

2:26

the subtle abnormality seen on the CT scan.

2:29

So in summary, this is a case of a patient

2:32

that presented with an unknown primary.

2:34

Initially, they could not identify the tumor.

2:37

We were a little bit suspicious on the CT scan.

2:39

But when we performed the PET/CT, we can see a focal

2:43

area of asymmetric uptake involving the right tonsil.

2:46

This was removed, and this was proven to

2:48

be squamous cell carcinoma of the tonsil.

2:51

So in this case, we were able to identify

2:53

the primary site in a patient that initially

2:56

presented with an unknown primary carcinoma

2:58

involving the upper aerodigestive tract.