Perineural invasion by carcinoma of the lower lip.

Extension of lip cancer to the mental nerve and perineural spread was found in four patients. The main complaint in all cases was sensory disturbance which preceded the diagnosis of recurrence by perineural spread as well as widening of the mandibular canal. In one patient, two cranial nerves, the trigeminal and the facial were involved and one patient had bilateral neural involvement. Three patients died within 1 year of the diagnosis of perineural spread. Prevention includes the separate examination of specimens at the resection line near the mental nerve, and follow-up by examination of the lower vestible, X-ray of the mandible and monitoring of sensory disturbance.