Pneumatization of the petrous temporal bone apices is an anatomical variant that may be bilateral or asymmetrical. It is important not to confuse it with a pathological lesion especially on MRI.

Benign lesions such as cholesterol granuloma and cholesteatoma are more likely to occur in a pneumatized petrous apex. Also, it can be a site for CSF fistula especially after skull base surgery (e.g. vestibular schwannoma surgery).