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This was a patient who presented with a mass in the

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left external auditory canal that was associated

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with a conductive hearing loss.

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We performed a skull-based MRI scan with and without

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contrast and the sequence to the far

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left is a CISS imaging sequence.

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This is a very nice sequence because you can do very

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thin section images, sometimes

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less than 1 mm in section thickness.

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It can be combined with the Vibe sequence, which

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allows you to do very thin section T1-weighted scan.

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On the CISS image, what we see is a very large mass

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that is expanding the external auditory canal, both

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the cartilaginous as well as the bony portion

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of the external auditory canal.

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It appears as if there's an opacification also of

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the middle ear cavity with this lesion and you have

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secondary obstruction in the mastoid air cells.

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In the mastoid air cells,

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there also looks like there's soft tissue

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abnormality, which may be extension through the bone

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into the mastoid from the external auditory canal.

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Post-gadolinium enhanced sequences were

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performed with fat suppression.

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On the post-gadolinium enhanced scan, we see that this

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is a very avidly enhancing soft tissue mass in the

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cartilaginous and bony portion of

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the external auditory canal.

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And that enhancement appears to extend even into the

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middle ear cavity, and potentially even around the

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region of the carotid artery in its posterior petrous

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portion here and extending to the petrous apex.

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So indeed,

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on the evaluation of the otoscopy report, this was a

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red vascular mass in the external auditory canal.

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On the coronal image, one can see that this is an

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avidly enhancing mass that appears to show

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evidence of dura-based enhancement.

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What I'm describing here is erosion through the

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tegmen tympani with the linear and thick enhancement

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that's occurring at the base of the left

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temporal lobe along the dura there.

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This is a very large mass, and one of the other

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features that you see with this large mass is what

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appear to be vascular flow channels within the mass.

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So we know that it's a red mass

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by virtue of the otoscopy.

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We had the confirmation that this is a vascular mass

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by virtue of the blood vessels that are within it.

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What was unusual about this case

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is the final diagnosis.

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Normally, we would be concerned about something like

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a vascular neoplasm or something that might even be

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a sarcoma in this location, given the erosion of the

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tegmen tympani. This ended up being a paraganglioma.

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Most of the time we think of paragangliomas

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affecting the jugular foramen or the tympanic cavity

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at the cochlear promontory or vagal

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glomus vagale ones at the skull base,

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or carotid body tumors at the carotid bifurcation.

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We don't usually think of the external auditory

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canal as a source for paragangliomas,

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but that was the final diagnosis, something that,

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again, surprised us.

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I don't think that there were any real clues to

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this being in particular a paraganglioma,

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other than being able to say that this is a highly

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vascular lesion and you have to be very careful

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in biopsying the lesion. Just to scroll once more,

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you can see that there really isn't a component

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that's extending to the jugular foramen or down

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the jugular vein. And there is, however,

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some element of the enhancing material

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that is in the middle ear cavity,

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which could have been the tip of an

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iceberg of a glomus tympanicum.