I AGREE WITH CARYOPTERIS BUT IT WOULDN'T HURT TO GET A BIOPSY TO MAKE SURE IT'S BENIGN AND IT PROBALLY IS, I HAVE CYSTS IN SEVERAL PLACES I SPOKE TO MY DOCTORS NURSE ABOUT THEM AND SHE TOLD ME I WAS A CYSTY PERSON. LOL.
Benign cysts, I should have said. Google foot ganglion cyst to read.
It is likely a ganglion. See link for pics.
http://www.google.com/search?hl=en&sugexp=kjrmc&cp=18&gs_id=o&xhr=t&q=ganglion+cyst+foot&nord=1&gs_sm=&gs_upl=&bav=on.2,or.r_gc.r_pw.,cf.osb&ion=1&biw=1366&bih=643&um=1&ie=UTF-8&tbm=isch&source=og&sa=N&tab=wi
They are benign.