Synovial cyst that compressed the peroneal nerve: case report.

We report a case of synovial cyst that induced the compression of the peroneal nerve. The patient presented with foot drop and impossibility to stand on his right heel associated with numbness of anterolateral surfaces of the right shin and the dorsal surface of the foot within a 1-month period. Based on the clinical examination and electroneuromyography data, the compression of nerve by soft elastic mass was confirmed. We treated the patient by total microsurgical excision of the soft elastic mass adherent to the right peroneal nerve at the top third of the patient's shin. Histological study revealed the cyst of synovial membrane. During the postoperative period, a force in extensors of the right foot was restored. On the seventh day, the patient began to step on his right heel, while the zone of tenderness and temperature hypoesthesia in the area of the peroneal nerve innervation remained.