Benign cystic lesions of peripheral nerves.

A patient with multiple cystic changes of the sural nerve, and another with a tarsal tunnel syndrome caused by invasion of the median plantar nerve by a ganglion in the tarsal tunnel, are presented. It is believed that there are three different kinds of benign cystic involvement of the peripheral nerves, multiple cystic degeneration of the nerve itself, invasion of nerves from outside by a ganglion and formation of simple cysts within the nerve proper, presumably as a result of trauma.