Spontaneous Bilateral Facial Paralysis Secondary to Metastatic Breast Cancer.

Sudden onset, bilateral facial paralysis is a rare clinical entity, representing less than 2% of all diagnoses of facial nerve paralysis. The differential for these patients is necessarily broad and includes numerous etiologies. Metastatic breast carcinoma to the bilateral parotid glands is also exceedingly rare with only 2 reported case reports noted in the literature, neither of which demonstrated facial nerve paralysis. Here, we report the only known occurrence of a patient presenting with synchronous bilateral facial nerve paralysis secondary to metastatic breast carcinoma to the bilateral parotid glands. This exceedingly rare clinical presentation was further confounded by the presence of autoimmune antibodies, highlighting the importance of the diagnostic process and maintaining broad clinical suspicion.