How is a paraganglioma (glomus tumor) diagnosed?
Examination of the eardrum (otoscopy) typically reveals a vascular, reddish mass behind the eardrum. A glomus tympanicum appears as rounded mass entirely contained in the middle ear, while a glomus jugulare may appear as the “tip of the iceberg”, with the majority of the tumor hidden below the eardrum. There may be enlarged blood vessels running towards the tumor along the eardrum or the ear canal. In addition, air pressure applied through the otoscope may cause a blanching effect on the tumor, which is filled with blood. When the question of a paraganglioma has been raised, CT and MRI scans are very useful. In the case of a glomus tympanicum, the CT scan usually demonstrates a rounded mass behind the eardrum with the same density as soft tissue. This must be distinguished from an abnormal carotid artery, which can have a similar appearance through the ear canal. For a glomus jugulare, the CT usually shows erosion of the bone over the bulb of the jugular vein at the skull base. MRI sca
