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One of the more aggressive cancers of the

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sinonasal cavity is what we call the SNUC tumor.

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This is called Sinonasal Undifferentiated Carcinoma.

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However, in the most recent 2023 revision of

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the World Health Organization analysis of the

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sinonasal tumors,

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they include Sinonasal Undifferentiated Carcinoma

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as a type of adenocarcinoma, and they have

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renamed some of these SNUC tumors based on their

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molecular genotype as the SWI/SNF — that switch,

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Sucrose Non-Fermentable Complex

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deficient Sinonasal Carcinoma.

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So you will see these terms used

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in histopathologic assessment.

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Suffice it to say that Sinonasal Undifferentiated

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Carcinoma is a very aggressive tumor that may be

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most commonly located in the ethmoid sinus and the

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superior nasal cavity. It grows very fast and at the

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time of the diagnosis, it's often quite large in size.

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As you can see, four centimeters on average. The

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prognosis is poor, although now that we understand

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the molecular genetics a little bit better, they're

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coming up with better chemotherapy for this tumor.

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It's a tumor that has aggressive

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bone erosive changes.

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Here's an example of a Sinonasal Undifferentiated

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Carcinoma on the sagittal T1-weighted scan.

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It's dark on the T2-weighted scan, and on

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the post-gadolinium enhanced scan, you see

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that it has grown through the lateral wall

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of the maxillary sinus and is into the

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masticator space, the infratemporal fossa.

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This is a portion of the temporalis muscle

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where it's growing along, so this aggressive

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growth right through the lateral

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wall of the maxillary antrum,

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the medial wall of the maxillary antrum into

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the sinonasal cavity, is one of the features

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of Sinonasal Undifferentiated Carcinoma.

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Unfortunately, it may very well look like a

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squamous cell carcinoma in the maxillary sinus.

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This is another PowerPoint example of

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a Sinonasal Undifferentiated Carcinoma.

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In this case, you see it in the ethmoid sinus

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with growth through the bone into the orbit.

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Again, you're probably getting used

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to these displacement of the medial

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rectus muscle in the extraconal

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soft tissues. In this case, when it's a smooth

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margination, once again, it may still be

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well-defined by the periorbita, and you

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may not need to do an orbital exenteration.

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Once we start seeing irregular irritation of

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the fat or tumor or edema that's medial to

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the medial rectus muscle, that's when we say

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that there's likely to be a requirement of

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an orbital exenteration to remove the tumor.

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For example, here we have a patient with

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another Sinonasal Undifferentiated Carcinoma.

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In this case, you can see tumor growth into the

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inferior rectus muscle and medial rectus muscle.

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There's irregularity to the intraconal fat.

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This patient's globe and orbit is

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probably going to need to be taken.

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You notice that in the superior

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orbit also, there's growth of

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tumor above the superior rectus muscle, and maybe

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even involving, certainly involving, the superior

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oblique muscle. The involvement intracranially,

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because there is just linear enhancement and

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no nodularity to it or growth into the brain

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parenchyma, or reaction of the brain parenchyma,

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it's likely that this can be removed

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with a craniofacial resection with

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radiation therapy treatment thereafter

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to clean up any microscopic disease.