Interactive Transcript
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Hello everyone, Sidney Levy here, continuing
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our discussion on the diagnosis and staging
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of oral cavity squamous cell malignancy.
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In this particular vignette, I'd like to focus on a couple
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of general principles that are very important when assessing
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squamous cell malignancy in the head and neck in general.
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Uh, in particular, I'd like to focus on marrow
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infiltration and perineural infiltration.
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These are features which are often components
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of the TNM staging of head and neck squamous
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cell malignancy, and we need to be familiar
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with the principles to help us diagnose them.
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Firstly, I'd like to start off with marrow infiltration
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and I'm going to use a case that we have been looking
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at, uh, of alveolar mucosal squamous cell malignancy,
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where there has been macroscopic
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mandibular cortical invasion.
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And I'd like to use it to illustrate the principles of
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marrow infiltration as well as perineural infiltration.
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The malignancy itself is here.
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It's an alveolar mucosal malignancy of the
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right mandibular alveolar mucosa, and it's
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directly invading the mandibular cortex.
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I have in front of me post-contrast T1-weighted imaging
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with fat suppression.
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And the reason I have that is because I'm looking
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for abnormal enhancement of bone or nerve.
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So for marrow infiltration, the features that I always
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look for are edema with loss of marrow architecture
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that's best assessed on T2-weighted imaging.
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And yes, the right mandible in the region of the ramus
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as well as the body near the tumor has abnormal edema.
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Let's have a look at the T1 weighted imaging
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to see if we can see abnormal architecture.
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And yes, there is abnormal architecture.
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There is loss of the normal definition of the
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trabecular of the mandible in this region.
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And then let's move on to post contrast imaging, where
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you can see there is abnormal enhancement of the marrow.
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So this satisfies all the criteria in addition to
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direct cortical destruction for marrow infiltration.
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Next we'd move on to the nerves.
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In this part of the body there is the inferior alveolar
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nerve, and that is the nerve which most commonly becomes
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involved with mandibular alveolar oral cavity malignancy.
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And what I'm looking for is
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abnormal enhancement of the nerve.
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But the key thing here is it has to be abnormal
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intraneural enhancement rather than perineural
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enhancement because there are vessels around the nerve
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which can appear, particularly veins, as enhancement.
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In addition to that, I'm also looking for
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loss of the interface between the edge of
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the nerve and the adjacent mandibular cortex.
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The last thing I look for as well, although it's
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not present in this case, is abnormal thickening
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of the nerve compared with the contralateral side.
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That can be a more difficult thing to
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appreciate, particularly within a bony canal.
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But in this case, there is high suspicion for
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perineural infiltration of the inferior alveolar
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nerve because there is abnormal intraneural
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enhancement, central intraneural enhancement.
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That's demonstrated here on the post-contrast
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imaging when compared with the pre-contrast imaging.
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And let me just magnify that because it's a subtle
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finding, and it can be difficult to appreciate.
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This inferior alveolar nerve is enhancing
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centrally compared with precontrast imaging.
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So in summary, marrow infiltration and perineural
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infiltration are key features of squamous
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cell malignancy in association with bone,
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and also within soft tissue.
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And the key features to look for are edema with loss
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of normal architecture of marrow, direct cortical
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destruction of bone, and lastly, marrow enhancement.
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For perineural infiltration, the key features to look
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for are abnormal thickening of the nerve compared with
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the contralateral side, loss of the normal interface
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between the nerve and the adjacent bone, and lastly, in
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this case, asymmetric central intraneural enhancement.
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These principles may be applied to any head and neck
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squamous cell malignancy or indeed other malignancies
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such as adenoid cystic carcinoma, for example.
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Thanks very much.
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