Multiple local and systemic entities have been implicated as causes of
tarsal tunnel syndrome. In this report, a 31-year-old man presented w
ith medial plantar nerve compression caused by an intraneural degenera
tive cyst of the posterior tibial nerve, Removal of the cyst and decom
pression of the nerve relieved his symptoms. This is the first time th
at such an entity has been reported as a cause of tarsal tunnel syndro
me.