Compression neuropathy of the common peroneal nerve secondary to a ganglion cyst

There are various causes of the common peroneal nerve palsy. However, common peroneal nerve palsy caused by ganglia are uncommon. We hereby present a case of a 55-year-old man with a 1 week history of foot drop and swelling in the region of the right leg. Physical examination and nerve conduction study studies confirmed a diagnosis of common peroneal nerve palsy. Magnetic resonance imaging (MRI) revealed a lobulated, elongated cystic-appearing mass anterior to the head of fibula. Surgical decompression of the nerve with removal of the mass was performed. Surgical pathology reports confirmed the diagnosis of a ganglion cyst. Findings on physical examination, nerve conduction study and MRI results of this interesting case are being discussed. We wish to highlight that even a tumour which is benign and within the nerve sheath can cause compression.