Unilateral congenital facial nerve paralysis secondary to a benign epithelioid peripheral nerve sheath tumor

A benign epithelioid peripheral nerve sheath tumor is described in the setting of congenital facial nerve (FN) paralysis. This is the first reported case in the English literature. A 10-month-old girl with unilateral congenital FN paralysis. Auditory brainstem evoked potential study, gadolinium-enhanced magnetic resonance imaging, temporal bone computed tomography, and transmastoid FN decompression with tumor resection. Follow-up for tumor recurrence and postoperative FN function. The child underwent a transmastoid FN exploration with resection of a 0.6-cm spherical tumor analyzed to be a benign epithelioid peripheral nerve sheath tumor. There is no evidence of recurrence, and FN function was unchanged at 1 year postoperatively. Benign epithelioid peripheral nerve sheath tumor can cause congenital facial nerve palsy.