An unusual cause of paralysis of the peroneal nerve-a case report.

A 12-year-old boy was referred to our clinic because of progressive paresis of left peroneal nerve. Ultrasound showed a cystic mass close to the proximity of the fibula neck. Puncture revealed jelly-like fluid, but that could not relieve symptoms. Six weeks after onset of symptoms, the boy had complete paresis. Peroneal intraneural ganglia are a rare entity of paralysis of the lower limb in children; more often these symptoms occur because of exostosis. Surgical exploration showed a cystic formation involving the common peroneal nerve. Total recovery of nerve function was seen two years later. Patients with exostosis showed varying outcomes. In children with symptoms suspicious of nerve compression, fast diagnosis and immediate treatment are mandatory to regain best possible recovery.