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Hello, everyone.

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It's Sydney Levy here continuing our discussion of

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the diagnosis and staging of oral cavity malignancy.

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I'd like to return to our case of left lateral

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oral tongue squamous cell malignancy, which

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we alluded to in the previous vignette.

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Today, I'd like to stage it for you formally

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according to the most recent eighth edition

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of the American Joint Cancer Committee

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guidelines for head and neck malignancy staging.

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So we have our example case with the pre-contrast,

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T1 weighted imaging without fat suppression.

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In the axial projection on the left, same thing, post-

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contrast fat-suppressed imaging on the right, still T1.

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Bottom left-hand corner, coronal T2

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weighted imaging with fat suppression.

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And bottom right, sagittal T1 post-

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contrast imaging with fat suppression.

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With these four sequences, you can achieve

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just about anything you need to with an

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oral tongue squamous cell malignancy.

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So these are my go-to sequences.

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So, T staging.

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First thing you have to do is to measure the lesion.

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If you have a choice between T1 post-contrast

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or T2, go for the T1 post-contrast because

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T2 sometimes has edema and normal mucosal T2

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hyperintensity, which can slightly overestimate

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your measurement if you're not careful.

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So we have a nice post-contrast T1 post-contrast

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image here.

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So let's use that.

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And it's either going to be sagittal or axial.

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It looks like it'll be sagittal in this case.

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So let's take a measurement and we

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have a just shy of five centimeters.

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So that automatically elevates

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it to either a T3 or a T4 tumor.

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The fact that it's more than four centimeters

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it's already going to be either a T3 or a T4.

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The next thing you need to do, and this is

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a new development since the beginning of

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2018, the most recent edition of the AJCC

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guidelines specifies depth of invasion.

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So depth of invasion is a measure of the thickness

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of the tumor and has been shown to correlate

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with prognosis and behavior of the tumor

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of oral cavity malignancies.

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So we need to take a measure of that.

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Take the thickest portion of the tumor.

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In this case, we're about

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1.5 centimeters so we are well over 10 millimeters

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and that makes this tumor a T4A tumor.

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So it's already in the category

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of moderately advanced disease.

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Because of greater than four centimeters

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maximal dimension and greater than ten

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millimeters depth of invasion using the

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post-contrast imaging wherever possible.

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What else do I need to say about the tumor?

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Does it cross the midline?

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Why is that important?

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Because the surgeon needs to decide

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how much to resect when treating this tumor.

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So, scanning through, there is

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one suspicious area, just there.

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Now, that particular site is

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bulging the midline of the tongue.

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So, just here, this is the midline of the tongue.

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And then we have a bulge, and then we keep going.

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So, you would need to raise suspicion that there

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is the beginning of crossing of the midline.

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And surgeons will usually take that to be

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likely when they're planning their surgery,

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so that they don't resect too little.

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So that's always important to

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mention with tongue tumors.

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The next thing is, does it involve

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contiguous oral cavity sites?

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And that's where your sagittal and

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your coronal imaging are so important.

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This tumor is directly extending

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into the floor of the mouth.

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So, what's the floor of the mouth?

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The floor of the mouth, for the purposes of

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staging, is considered to be the undersurface

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of the tongue, as well as the mucosa

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overlying the extrinsic tongue musculature.

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So this tumor is clearly extending

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inferiorly into the floor of the mouth.

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Once it does that, we now need to decide,

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is it invading adjacent structures?

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Previously, it used to be very important

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to describe which, if any, of the extrinsic

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muscles of the tongue were involved by the tumor.

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That is now less important because of

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the depth of invasion criterion, which

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was introduced at the beginning of 2018.

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So this tumor is already advanced, moderately

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advanced, because of depth of invasion.

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But it is still worthwhile to mention that

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the tumor is involving the left genioglossus.

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So often, as a general rule, oral cavity malignancies

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of the floor of the mouth or the tongue will first involve

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the genioglossus before they involve other extrinsic

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muscles, such as the hyoglossus or the myelohyoid.

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Next, we need to talk about the nodes.

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We've decided this is a T4A tumor.

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In our next vignette, we will discuss how

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we stage the nodes and distant disease.

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Thank you.