Undiagnosed squamous cell carcinoma of the forehead presenting as a Tolosa-Hunt syndrome.

Squamous cell carcinoma (SCC) is the second most common periocular skin cancer. We describe a case of invasive squamous cell carcinoma arising from actinic keratosis and causing orbital and intracranial invasion via perineural spread. Perineural invasion (PNI) is a known feature of SCC and very rarely basal cell carcinomas of the head and neck. A high degree of clinical suspicion is necessary to diagnose PNI. Varied clinical presentations have been described for this form of dissemination, including orbital apex syndrome as in our case. Prognosis is poor, with death resulting in over 50% of cases at 5 years.