Squamous Cell Carcinoma with Clinical Perineural Invasion: Challenges and Review in Single Case Study.

Perineural invasion is a rare prognostic finding of squamous cell carcinomas that is associated with a poor prognosis. Early recognition of perineural invasion is imperative to improving treatment and lowering recurrence. Here we report the case of a 77-year-old Caucasian male with a suspicious mass on his forehead. Diagnosis confirms a squamous cell carcinoma with T1-weighted MRI findings significant for perineural invasion of the right supratrochlear nerve based on nerve thickening with loss of fat. Due to his immunocompromised status and the presence of positive margins after wide local excision, the patient is treated with adjuvant external beam radiotherapy of the nerve course. Risks of radiation-induced optic neuropathy should be weighed against recurrence in tumors that invade the trigeminal nerve.