Petrous Apex Lesions

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The petrous apex is located in the temporal bone — one of the bones of the skull that houses the structures of the ear. The petrous apex is a difficult area for surgeons to get to; it is essentially just off the midline of the skull base.

Petrous apex lesions typically are not cancerous, although tumors can erode into the petrous apex from other areas of the skull base (examples include chordoma, chondrosarcoma, metastases and nasopharyngeal carcinoma). 

Inflammatory or congenital lesions of the petrous apex include:

  • Cholesteatoma or epidermoid tumors (benign cysts filled with dead skin)
  • Cholesterol granuloma (benign cysts filled with a thick material much like crankcase oil)
  • Fat in the bone marrow of a petrous apex that does not contain any air space
  • Fluid in a petrous apex air cell (like fluid in a sinus)
  • Mucocele (a benign, expanding cyst filled with mucus)
  • Benign tumors of the petrous apex include meningioma, schwannoma and paraganglioma (glomus tumor). 


Serious infections of the petrous apex (petrous apicitis) can cause:

  • Severe headache
  • Ear pain
  • Pain behind the eye
  • Pus drainage from the ear
  • Hearing loss
  • Facial weakness
  • Double vision

These types of infections may require intravenous antibiotics and surgical drainage.


CT and MRI scanning are essential for evaluating the lesions. Occasionally, a petrous apex lesion is diagnosed incidentally on an MRI obtained for other reasons.

Treating Petrous Apex Lesions

Often, these lesions are simply normal anatomic variants that will not cause problems (such as bone marrow in the petrous apex).

Treatment options include:

  • Watchful waiting and observation with imaging to document any growth of the lesion (such as for small cholesterol granulomas or fluid in a petrous apex air cell)
  • Surgery either to open the cyst and drain the fluid (although there is a risk of recurrence of the cyst), or to remove the lesion

Your surgeon will discuss individual treatment strategies with you.


Content was created using EBSCO’s Health Library. Edits to original content made by Rector and Visitors of the University of Virginia. This information is not a substitute for professional medical advice.