On the T2 axial image there is a round mass of mixed signal in the right cerebellopontine angle. It causes slight displacement of the brain stem medially, and extends into the auditory canal on the right. The edge of the mass makes an acute angle with the petrous bone.
On the T1 coronal image there is intense enhancement. The tail within the canal is clearly seen.
A CT study of the same patient was also available: an image is included for comparison.
Right acoustic neuroma (schwannoma)
Acoustic neuromas account for 80% of cerebellopontine angle tumours. They are more common in females and in patients with neurofibromatosis, especially of the central type (NF type 2).
The main differential diagnosis is a meningioma. These account for 15% of CPA masses and also enhance brightly. However they do not tend to extend into, or arise from, the canal and often have a broad base with a less acute angle between tumour and bone (the ‘tail’). There may be associated bony sclerosis.