Facial Paralysis Secondary to Extensive Perineural Spread of Adenocarcinoma of the Parotid Gland Identified by PET/CT.

Brain MRI in an 82-year-old man with presumed Bell's palsy revealed a clinically unsuspected right parotid gland mass but no other acute findings. Biopsy revealed poorly differentiated adenocarcinoma. Staging F-FDG PET/CT revealed an FDG-avid parotid mass, abnormal FDG uptake along the course of the facial nerve from mass to skull base, and multiple FDG-avid right level II neck lymph nodes and hepatic metastases. The PET/CT findings and prolonged clinical course suggest that diffuse perineural spread of tumor from a smoldering parotid neoplasm, and not idiopathic Bell's palsy, was responsible for the patient's facial paralysis.