0:00

As we saw with that graphic from Jatin Shah's Head and

0:04

Neck Surgery textbook, overlapping sites is a very

0:10

common location for malignancies of the sinonasal cavity.

0:14

Here, for example, we have a mass, which is growing

0:18

bilaterally into the ethmoid sinuses, but also

0:20

into the nasal cavity, so an overlapping site and

0:24

potentially even into the maxillary antrum in this case.

0:28

Once again, the lesion is dark on the T2-weighted

0:31

scan and shows some element of contrast enhancement.

0:36

You notice that the left maxillary sinus is

0:40

not showing solid enhancement and has brighter

0:43

signal intensity on the T2-weighted scan.

0:45

This helps us in defining the margins of

0:48

the tumor because obstructed secretions,

0:51

unless they're very hyperproteinaceous,

0:53

by and large, are going to be bright on the T2-weighted scan

0:57

until they get out to the 30% protein concentration,

1:01

if you recall that graphic from Peter Som.

1:04

So in this case, we can pretty much determine that this

1:08

is the cancer, this is the obstructed maxillary sinus.

1:12

This would be much more difficult to define on

1:15

CT scanning because the tumor and the hyperdense

1:19

secretions may look exactly alike.

1:22

For that reason, MRI is the main driver and the workhorse

1:26

for the evaluation of neoplasms of the sinonasal cavity.

1:31

Nonetheless, with few exceptions, the signal

1:34

intensity of the different histologies of

1:38

malignancy of the sinonasal cavity will be similar.

1:40

I cannot tell you whether this

1:42

is a squamous cell carcinoma.

1:44

Or an adenocarcinoma.

1:46

I can't tell you whether this could be a lymphoma.

1:48

They're all gonna be dark on T2.

1:51

They're all gonna show enhancement on T1.

1:53

Sometimes we will get lucky with some of the lesions

1:57

that may have a chondromatrix, where we would

2:00

call it a chondrosarcoma, or what we will see

2:04

with olfactory neuroblastomas where you may have

2:06

intracranial cysts associated with the neoplasm.

2:10

This patient, we would not be able to say whether

2:13

this was an inverted papilloma with secondary

2:15

squamous cell carcinoma on the histology.

2:18

So again, a bit nonspecific.

2:20

More importantly, is there

2:23

involvement of the orbital contents?

2:25

Because a tumor that grows into the orbital

2:28

where you have to have an orbital exenteration

2:31

is a lot more disfiguring and worse prognosis

2:35

than one where the periosteum of the

2:38

orbit is intact.

2:40

Similarly, we look for the intracranial extension

2:43

to see whether there's any dural or parenchymal or

2:47

pial enhancement that would suggest intracranial

2:50

extension, which would lead to a craniofacial

2:53

resection, and again, a worse prognosis.

2:57

Then we also look for periorbital spread, which we mentioned

3:00

with adenoid cystic carcinoma in the previous case

3:03

where there may be intracranial spread along the

3:06

cranial nerves, usually the fifth cranial nerve.

3:10

Here's another example of where the tumor is

3:15

identified very nicely on the T2 MRI scan as

3:19

darkened signal intensity with obstructed secretions

3:23

in the left maxillary antrum here on the CT scan.

3:27

You probably would assume that this was obstructed

3:31

secretions, but that differentiation between the

3:34

tumor versus the obstructed secretions is much

3:37

better visualized on the MRI scan, particularly

3:40

T2-weighted scanning and post-gadolinium

3:43

hand scanning than it is on the CT scan.

3:47

As I mentioned, squamous cell carcinoma is the most

3:50

common cancer to be identified in the maxillary sinus.

3:55

In the nasal cavity.

3:57

It sort of competes with melanoma, which is

4:01

another of the common nasal cavity malignancies.

4:05

It's less common in the ethmoid

4:06

sinus where adenocarcinomas.

4:09

Predominate when we have squamous cell carcinoma,

4:12

like with adenoid cystic carcinoma, a minor

4:15

salivary gland tumor, we look for perineural spread.

4:18

Fortunately, nodal metastases in sinonasal

4:22

malignancies are pretty uncommon.

4:26

This is the T staging of maxillary sinus cancer.

4:30

You see T1 limited to the sinus, T2 bone erosion,

4:35

potentially even extending into the hard palate.

4:38

Or into the nasal cavity, T3 involvement

4:41

of the posterior wall of the maxillary

4:43

sinus where we'll go into the perianal fat.

4:46

The subcutaneous tissues as we saw with the example

4:49

from the MRI that we saw involvement of the floor

4:52

or medial wall of the orbit, or the pterygopalatine fossa,

4:57

T4A invasion into the anterior orbital contents.

5:00

By this we mean the anterior globe structures, the skin.

5:04

The OID plates, the infratemporal fossa,

5:07

which is analogous to the masticator space.

5:10

The cribriform plate, where we

5:12

potentially are talking about intracranial

5:14

extension, sphenoid or frontal sinuses.

5:16

And T4B, which is generally unresectable

5:19

disease, is disease that extends into the

5:22

orbital apex where it may affect the optic

5:24

nerve, the dura, the brain, the middle cranial

5:27

fossa, the cranial nerves, nasopharynx, orbits.

5:30

So these are generally treated

5:31

with chemoradiation therapy.