Facial nerve choristomas are rare, being characterized by non-neoplastic proliferation of smooth muscle cells and fibrous tissue. Facial nerve choristomas presumably can occur anywhere along the course of the facial nerve (CN VII), although the only cases reported are in the internal acoustic meatus and in the region of the geniculate ganglion.
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Clinical presentation
This is with a lower motor neuron facial palsy. However, choristomas have also been reported affecting other cranial nerves as well as the eye.
Radiographic features
They are indistinguishable from vestibular schwannomas on imaging, appearing as small circumscribed enhancing soft tissue nodules on contrast-enhanced MRI, which is the imaging modality of choice.
Treatment and prognosis
Complete surgical resection is curative and no adjuvant therapy is required. However, there can be morbidity related to the surgery including facial nerve palsy and hearing loss due to intra-operative nerve injury. Damage to the geniculate ganglion results in additional morbidity when intracranial exposure of the labyrinthine segment of the facial nerve is required to resect the tumor 1.