Perineural invasion detected by high-field 3.0-T magnetic resonance imaging.

The presence of perineural invasion (PNI) with cutaneous squamous cell carcinoma portends a poor prognosis. PNI may be detected radiographically or clinically, with motor or sensory deficits, and is confirmed by histologic evaluation. Recent interest has grown regarding the role of imaging in determining the presence of PNI and its preoperative implications. We report on a patient with cutaneous squamous cell carcinoma invading the parotid gland with clinical evidence of facial nerve weakness. On standard 1.5 Tesla (T) magnetic resonance imaging (MRI), bilateral parotid glands were symmetric; however, a second high-field 3-T MRI revealed asymmetric enhancement of the left facial nerve at the stylomastoid foramen and extending throughout the left parotid gland. PNI was later confirmed on histopathology. The presurgical determination of PNI was essential in our mapping the exact tumor location and in our surgical planning.