Facial Nerve Hemangioma

Hemangioma of the facial nerve is a rare benign entity, representing less than 1% of temporal bone tumors. The majority of patients present in the 3rd to 6th decade of life.

The most common location for facial nerve hemangiomas is the geniculate fossa followed by the internal auditory canal. This distribution corresponds to the density of capillary plexus surrounding the facial nerve (highest in the region of the geniculate ganglion).

These hemangiomas range in size from 2 mm to 20 mm, but are usually symptomatic early (usually < 10 mm). Hemangiomas in the geniculate fossa usually present with slowly progressive facial nerve paralysis. Invasion of the internal auditory canal and cochlear otic capsule can result in sensorineural hearing loss and pulsatile tinnitus.

CT reveals a lesion with irregular and amorphous margins. The typical honeycomb appearance of hemangiomas is pathognomonic, but is seen in about 50% of cases. Without these spicules, the differential widens to include schwannoma and, less commonly, meningioma.

MRI reveals variable signal intensity on T1-weighted images and increased signal intensity on T2-weighted images with hypointense foci corresponding to the ossific matrix of these lesions (the honeycomb spicules mentioned above). There is usually avid contrast enhancement. The differential consideration with these MRI findings includes normal facial nerve enhancement, Bell palsy, schwannoma, and perineural spread of a parotid malignancy.

Our case shows soft tissue prominence and enlargement of the anterior genu of the right facial nerve in the region of the geniculate ganglion. Spicules are seen associated with this lesion, best appreciated on the sagittal reconstructions.

References

Mijangos SV, Meltzer DE. Case 171: facial nerve hemangioma. Radiology. 2011 Jul;260(1):296-301.