Petrous apex lesion
Petrous apex lesions are defined differently by otologists and neurosurgeons. Traditionally, otologists consider petrous apex lesions as those involving bone erosion or the petrous bone itself (e.g., congenital cholesteatomas, facial nerve neurinomas, and cholesterol granulomas). Neurosurgeons include other lesions related to the petrous apex; they do not necessarily involve bone erosion (e.g., petroclival meningiomas, trigeminal schwannomas)
Differential diagnosis
There is a wide differential diagnosis of petrous apex lesions:
asymmetrical marrow
petrous apex cephalocoele
petrous apicitis
cholesterol granuloma: most common cystic appearing lesion
mucocoele of petrous apex
Schwannoma
Skull base chondrosarcoma: most common solid lesion
Skull base chordoma: tends to be more midline but can involve the petrous apex
Plasmacytoma
Metastatic lesion
Langerhans cell histiocytosis
Aneurysm of terminal internal carotid artery.