Facial nerve haemangioma
Facial nerve haemangiomas (aka benign vascular tumour of the facial nerve) along with facial nerve schwannomas make up the majority of primary tumours of the facial nerve, which is a very rare entity. It has a predilection for the region around the geniculate ganglion (although even more rarely seen in the IAC), compared to schwannomas which can occur anywhere along the nerve. The bony margins are indistinct, as although the tumour is localised it is unencapulated, enabling them to be distinguished from schwannomas, which like schwannomas elsewhere (think jugular foramen lesions) have well defined remodeled margins.
Both capillary and cavernous subtypes are identified histologically and both types can be seen within the one tumour.
A variant is the ossifying haemangioma of the facial nerve, which has a distinctive appearance; radiating outwards from its center is a 'spoke wheel' or 'honeycomb' arrangement of ossification.
These lesions typically affect middle aged patients and are very slow growing. At presentation they are usually approximately 1cm in size, and typically cause significant symptoms despite their small size. This is another distinguishing feature from schwannomas which despite larger size often have few symptoms. Typically they present with facial nerve palsy which can be rapid onset mimicking a Bell's palsy. Sensory neural hearing loss (SNHL) and tinnitus can also be presentations.
On MRI they tend to be:
- iso or slightly hypointense on T1WI
- hyperintense on T2WI
- intense contrast enhancement
see also:
- facial nerve schwannoma
- facial nerve malignant schwannoma
- facial nerve perineurioma
- meningiomas arising from the geniculate ganglion have been reported
- facial nerve metastases, haematogenous and retrograde spread.
