Hypopharynx - Piriform Sinus Carcinoma - Local Spread
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Hello everyone.
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Dr. Sidney Levy here, continuing our discussion of the diagnosis
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and staging of hypopharyngeal squamous cell malignancy.
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So using our example case of a left piriform
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sinus squamous cell carcinoma, I'd like to
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discuss the pattern of spread of these tumors.
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Firstly, they may spread from the apex of the piriform
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sinus inferiorly and medially to the post-cricoid region.
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So if I try and draw that for you.
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This is the tumor here,
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now if you have a look, it is spreading medially,
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but it's not anterior; it's posterior, so this tumor is
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actually spreading medially across the midline, which is
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here, because the structures have been distorted somewhat
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by the tumor, via the posterior hypopharyngeal wall.
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It's posteriorly, not anteriorly.
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Now remember, it is difficult to distinguish the post-
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cricoid space from the posterior hypopharyngeal wall.
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But the post-cricoid space is actually here.
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One pattern of spread is via the post-cricoid region,
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medially, but another pattern of spread is via the posterior
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hypopharyngeal wall, also medially, depending on whether
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the tumor chooses to spread more anteriorly or posteriorly.
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Other patterns of spread involve spreading
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anteriorly into the larynx itself, and the
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larynx here is distinguished by its cartilages.
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So we have the thyroid cartilage here, we have the
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cricoid cartilage here, we're just below the level of
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the arytenoid cartilages by this stage, and we have the
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supraglottic larynx heading into the glottis in here.
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So piriform sinus tumors may choose to spread anteriorly,
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directly into the larynx.
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Another important pattern of spread is posteriorly, into
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the retropharyngeal space or prevertebral musculature.
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And, as you might imagine, this is direct spread, which
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can eventually reach bone, although that is very uncommon.
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Lastly, there is no barrier to these tumors
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spreading laterally into the parapharyngeal tissues.
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And it is possible, but not common, that
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the internal carotid artery may be entirely
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encased by tumor, should it spread far enough.
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Lastly, there is also no reason why hypopharyngeal piriform
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sinus tumors cannot spread superiorly into the oropharynx
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via the epiglottis or the posterior oropharyngeal wall.
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So there are a lot of ways in which these tumors can
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spread, and it's important to be aware of the anatomy of
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the region, in particular the anatomy of the larynx,
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which is medial and anterior to the piriform sinus.
Sidney Levy, PhD, MBBS
Radiologist and Nuclear Medicine Specialist
I-MED
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