Skin cancer of the head and neck with perineural invasion.

Perineural invasion occurs in 2% to 6% of cutaneous basal and squamous cell carcinomas of the head and neck and is associated with midface location, recurrent tumors, high histologic grade, and increasing tumor size. Patients may be asymptomatic with perineural invasion appreciated on pathologic examination of the surgical specimen (incidental) or may present with cranial nerve deficits (clinical). The cranial nerves most commonly involved are the 5th and 7th nerves. Magnetic resonance imaging is obtained to detect and define the extent of perineural invasion; computed tomography is used to detect regional lymph node metastases. Patients with apparently resectable cancers undergo surgery usually followed by postoperative radiotherapy. Patients with incompletely resectable cancers are treated with definitive radiotherapy. The 5-year local control, cause-specific survival, and overall survival rates are approximately 87%, 65%, and 50%, respectively, for patients with incidental perineural invasion compared with 55%, 59%, and 55%, respectively, for those with clinical perineural invasion.