Peroneal nerve palsy due to synovial cyst: An unusual cause of foot drop in a nine-year-old child.

Foot drop is the inability to dorsiflex the foot, and peroneal nerve palsy, a common cause of foot drop, is a rare condition in pediatric patients. Herein, we present a nine-year-old patient with foot drop due to peroneal nerve palsy verified by electrophysiologic examination. A cystic mass was observed in ultrasonography and magnetic resonance imaging, and hyaluronic acid was detected in the cystic material by histopathological examination. The patient was referred to surgery, and one month after surgery, an increase in muscle strength was observed. It should be kept in mind that peroneal nerve palsy due to synovial cysts may cause foot drop in pediatric patients.