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Hello everyone, Sydney Levy here continuing our

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discussion of the formal TNM staging of oral cavity

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malignancy according to the most recent American Joint

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Cancer Committee guidelines published in early 2018.

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We have our example case of an oral tongue

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malignancy, which we have already staged

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according to T stage in our last vignette.

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In this vignette, I would like

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to focus on the lymph nodes.

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There has been a major change since the 7th

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edition guidelines in that now every oral cavity

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or oropharyngeal or indeed upper aerodigestive

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tract malignancy needs to be documented

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as either human papillomavirus negative or

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positive before a formal stage can be given.

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And that's a very important change

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because there has been a change in the

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demographic of which people get

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oral cavity and oropharyngeal malignancy.

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We are now seeing a younger demographic of

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people who have human papillomavirus positivity.

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And those people tend to have a better

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prognosis, and it's resulted in a

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requirement to change the N staging.

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So after that introduction, I'd like to go on to

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our study in which we have three lymph nodes that we

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can see that are clearly morphologically abnormal.

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I have the pre-contrast T1 and the post-contrast T1

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with fat suppression in the top half, and I have the

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T2 with fat suppression in the coronal projection,

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and the sagittal post-contrast T1 with fat suppression.

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The first thing you need to do is to

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identify whether lymph nodes are present

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on one or both sides of the neck.

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In this case, it is bilateral and

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this already upgrades the N stage.

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I'm going to begin with the N stage for an

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HPV, or human papillomavirus, negative tumor.

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There are three lymph nodes here,

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two on the left, one on the right.

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They are situated in left levels 2a extending into

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3 and on the right situated within right level 2a.

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You identify that to refresh people's memory

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by the inferior border of the hyoid bone.

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That is the boundary between level

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2 and level 3 in levels of the neck.

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The next thing you need to do is to measure the

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maximal dimension of the largest lymph node.

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That is often seen in the sagittal projection.

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So that's something to keep in mind.

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It's often best to look in the sagittal projection

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because that is usually where you will get your

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maximal dimension for levels two, three, and four.

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In this case, we have a 27 millimeter

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lymph node and therefore it falls

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under the threshold of six centimeters,

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which is important for staging.

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Lastly, there is no radiologic evidence

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to suggest extranodal extension,

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such as an infiltrative nodal margin.

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So we can stage this tumor, we are

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calling HPV negative, as an N2C tumor.

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And the reason for that is bilateral

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lymphadenopathy, and none of the lymph

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nodes are more than six centimeters.

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And there is no radiologic

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evidence of extranodal extension.

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Lastly, we must comment as to whether

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there is any evidence of distant disease,

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and this is where modalities such as

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PET CT and CT assume primary importance.

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There is no evidence of distant

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disease in this particular example.

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So in summary, for an HPV negative tumor,

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this is an N2C tumor, it's bilateral,

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and the lymph nodes measure less than 6 cm.

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The last thing to remember is if it's an HPV positive

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tumor, which are more common in the oropharynx but

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do occur in the oral cavity, it becomes an N2 tumor.

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And the way that we work that out,

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it's actually a lot simpler.

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If you have bilateral disease and it's less

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than 6 centimeters, it's N2, as opposed

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to ipsilateral disease, which is N1.

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Thank you.