Perineural Skull Base Metastasis

This 75 year-old male patient had a history of left parotid acinic cell carcinoma treated by parotidectomy. There is an expansile, enhancing infratemporal and skull-base lesion. There is subtle enhancement and thickening in the region of the carotid sheath, suggesting perineural spread via the glossopharyngeal, vagus or spinal accessory nerves. This is an unusual route for perineural spread from the parotid, with facial nerve or trigeminal nerve involvement being more common.
Any malignant tumour may undergo perineural tumour spread. The tumours with the greatest propensity for this form of spread are: adenoid cystic carcinoma; squamous cell carcinoma; desmoplastic melanoma; non-Hodgkin lymphoma; and mucoepidermoid carcinoma. Perineural tumour spread adversely affects patient prognosis, with increased local recurrence, distant metastases and meningeal carcinomatosis.
Reference: Harnsberger R, et al. Diagnostic Imaging: Head and Neck. Amirsys 2004.
Credit: Dr Laughlin Dawes
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