Cysts are soft tissue masses that can be fluid-filled or solid in nature. Most of the time, cysts are benign but cause pain because they are taking up space in the foot or rubbing on the inside of shoes. The most common cysts found in the foot and ankles are ganglion cysts, mucous (synovial cysts), lipomas (fat), and giant cell cysts. These cysts may be easily removed with surgery. After removal, the mass is sent to the pathology lab to determine the type of mass and if any malignant cells are present. If you have what you believe is a cyst or a growth on your foot/ankle, it should be evaluated by a foot and ankle specialist.