Normal variants: Aberrant internal carotid artery

An aberrant carotid artery can present as a red mass posterior to the tympanic membrane. This must be differentiated from a glomus tumor (which can also appear red on exam), as a biopsy could be catastrophic.

Case #1

Case #1a

Axial computed tomogram at the mid ear level

The left internal carotid artery (arrows) has an aberrant course which traverses the middle ear. Following the course of the carotid canal aids in diagnosis of this retrotympanic mass.

Case #1b

Coronal computed tomogram at the mid ear

The aberrant carotid artery could easily be mistaken for a glomus tumor on coronal imaging alone.
 
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