High-resolution CT of mastoid sinus pneumocele with external auditory canal stenosis.

A 34-year-old man presented with tinnitus and conductive hearing loss. CT demonstrated an expansile, air-containing cavity contiguous with mastoid air cells, narrowing the external auditory canal. This is a case of symptomatic pneumocele resulting in an air collection beneath external canal lining, possibly related to an abnormality in mastoid fusion.