Larynx - Subglottic Carcinomas: Patterns of Spread & Differential Dx
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Hello everyone.
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Dr. Sidney Levy here, continuing our discussion of the
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diagnosis and staging of laryngeal squamous cell malignancy.
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I'm at the level of the subglottis at the moment.
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I've been using this large transglottic tumor as an
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example for us to see how tumors in this region spread.
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Subglottic tumors tend to spread
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in one of four or five ways.
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There tends to be a pattern of circumferential
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spread, so sometimes all you will see is a
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circle or partial circle of tumor internal to the
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cricoid ring involving only the subglottic mucosa.
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They can also spread in a cephalad fashion to involve
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the true vocal cords or indeed the supraglottis.
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Sometimes they spread anteriorly directly
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through structures such as the cricothyroid
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membrane or the cricotracheal membrane.
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And they can also spread directly posteriorly into
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the cricoid cartilage and the cervical esophagus.
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Lastly, uncommonly, they may also
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spread, uh, inferiorly into the trachea.
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In this case, the tumor is primarily situated
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within the supraglottis and the glottis, and
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the subglottis has been the destination of
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spread rather than the origin of the tumor.
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Last thing to consider is the differential
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diagnosis of subglottic tumors.
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These are glottic tumors, and the best thing to do there
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is to try and identify the level of the commissures and
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the true vocal cords and make an assessment as to whether
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you think the tumor is centered at the level of the
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glottis or below that at the level of the subglottis.
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You can also see conditions as with other laryngeal
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tumors such as, uh, chondroid tumors, chondrosarcoma,
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or autoimmune conditions such as
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rheumatoid arthritis, sarcoidosis.
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Rarely, trauma may be mistaken for a tumor if
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there has been a traumatic event to the larynx.
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Sometimes, uh, the way in which
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that heals can look tumor-like.
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And lastly, minor salivary gland malignancies
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such as adenoid cystic carcinoma can also,
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uh, be present in the subglottis, and often
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this diagnosis is made by the pathologist.
Sidney Levy, PhD, MBBS
Radiologist and Nuclear Medicine Specialist
I-MED
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