Contralateral cranial polyneuropathy due to perineural invasion by a cutaneous squamous cell carcinoma.

Cutaneous malignancies may spread to underlying nerves, a process known as perineural invasion (PNI). We report a patient who was found to have PNI presenting as a cranial polyneuropathy on the contralateral side of the face many years after the resection of a squamous cell carcinoma. All diagnostic testing was unrevealing until nerve biopsy was performed. This emphasizes the long asymptomatic period between treatment of a cutaneous malignancy and detection of PNI, and the development of PNI at a site distant from the original malignancy. Biopsy of a clinically involved nerve may permit diagnosis of PNI when other studies are normal.