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N and M Staging of Floor of Mouth Squamous Cell Malignancy

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Hello, everyone.

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Sidney Levy here, continuing our discussion of the

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staging of oral cavity squamous cell malignancy,

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in particular, this floor of mouth lesion.

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So this lesion is associated with extensive

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bilateral cervical lymphadenopathy.

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And it's important from a treatment perspective to be

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able to specify which levels these lymph nodes belong to.

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And in this particular case, uh, if you haven't

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already looked at it, I would, uh, suggest that you

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review the vignette, uh, concerned with, uh, lymph

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node levels of the head and neck, as it will help

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you orient, in particular, with regards to this case.

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Taking you through the case, we can see multiple,

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uh, abnormally enlarged and morphologically

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abnormal lymph nodes on both sides of the neck.

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Starting off here we are in level 2B on the left,

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and we know that because we can see the internal jugular

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vein with a fat plane between it and the lymph node.

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So level 2B, level 2A, just

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anterior to the jugular vein on the left.

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On the other side, we have

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level 2A on the right.

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As we head forward, we can see evidence of

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likely abnormal level 1B lymph node on the right.

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Likely abnormal level 1A lymph node anteriorly.

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Medial to the medial border of

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the anterior belly of digastric.

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That's how you tell the difference between 1A and 1B.

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Further down, likely abnormal right level 3 lymph node.

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Inferior to the inferior border

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of the hyoid bone on the right.

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Now, because there's so many abnormal lymph

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nodes, especially on the left-hand side, and

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treatment needs to be planned for this patient,

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which will no doubt include radiotherapy.

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This is the patient that would

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benefit greatly from a PET CT scan.

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So if it hasn't already been performed, I would suggest

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it because it will help distinguish between borderline

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nodes on CT or MRI that are enlarged but not necessarily

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completely morphologically abnormal and may be reactive.

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The truly abnormal nodes will be intensely

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FDG avid, whereas the reactive nodes may

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be only mildly to moderately FDG avid.

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So this is a good case for that situation.

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Not to mention, because it's such an extensive local tumor

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and there is extensive bilateral cervical lymphadenopathy,

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we need to assess the rest of the body in detail to

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make sure that there isn't distant metastatic disease.

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And that may be difficult with other modalities.

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Lastly, there is no radiologic evidence to suggest

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extranodal extension, such as an infiltrative nodal margin.

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As alluded to in a previous vignette dedicated to the

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N staging of oral cavity squamous cell malignancy,

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there are two N staging systems, and they depend

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on the human papillomavirus status of the patient.

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Thank you.

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If the patient is HPV-negative, this is an N2C tumor because

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there is bilateral nodal metastasis, which is less than 6 cm.

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We can see visually that none of these lymph nodes

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are greater than 6 cm in dimension, maximal dimension.

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And there is no radiologic

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evidence of extranodal extension.

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If, however, the patient is HPV positive, it will be

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considered an N2 tumor due to the same criteria, but keep

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in mind the HPV-positive patients have a better prognosis

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and their treatment regimen is slightly different.

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So it's important that if you're going to provide an N

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stage, you need to know the HPV status of the patient.

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In this particular field of view, there was no evidence

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of distant metastatic disease, so it's an M0 staging.

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So in summary, this patient has an N2C if HPV negative,

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or N2 if HPV positive, M0 tumor of the floor of mouth.

Report

Description

Faculty

Sidney Levy, PhD, MBBS

Radiologist and Nuclear Medicine Specialist

I-MED

Tags

PET

Oral Cavity/Oropharynx

Nuclear Medicine

Neuroradiology

Neuro

Neoplastic

MRI

Head and Neck

CT

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