====== Petrous apex lesion ======

[[Petrous apex]] [[lesion]]s 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 meningioma]]s, [[trigeminal schwannoma]]s)

===== Differential diagnosis =====
There is a wide differential diagnosis of petrous apex lesions:

asymmetrical marrow
    
petrous apex cephalocoele 

petrous apicitis
    
[[Petrous bone cholesteatoma]].


    
cholesterol granuloma: most common cystic appearing lesion 
    
mucocoele of petrous apex 

[[Petrous apex meningioma]].

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.