Cysts can develop on any part of the body. On the foot, they usually develop under the skin; however, they can also emerge more deeply in the bones, joints, or ligaments. Cysts are fluid-filled and can cause pain and discomfort, especially if they are located in an area susceptible to footwear pressure or infringe upon a nerve. Cysts can develop from something as simple as improperly-fitting footwear; they can also result from foot injuries.

There are several types of cysts that can impact the feet. One of the most common is ganglion cysts that form on a tendon or joint. These cysts are filled with a jelly-like fluid and form a knot or mass underneath the skin that’s size can vary over time. Synovial cysts also form in tendons or joints. Doctors can use diagnostic tests such as X-rays, CT scans, ultrasounds, and MRIs to view and diagnose cysts.

Cysts on the feet can be treated with orthotics that alleviate pressure. Doctors may monitor cysts over time to detect changes in size or composition; they may also remove fluid from a cyst. Sometimes, after extracting fluid, treatment may involve a steroid injection into the cyst. It is not uncommon for cysts to return.