A ganglion cyst is a non-cancerous, fluid-filled sac that arises from the synovial fluid surrounding joints or tendons. While they are most commonly found on the wrist, ganglion cysts can also appear on the feet, particularly around joints or tendons. These cysts are typically round or oval, soft to the touch, and can vary in size. Though often harmless, their location and size may cause discomfort or interfere with footwear.
The exact cause of ganglion cysts is not fully understood. However, they are believed to form as a result of trauma - either a single injury or repetitive microtrauma to a joint or tendon. This trauma may cause synovial fluid to leak and collect in a surrounding sac, forming the cyst. While they can occur spontaneously, individuals with joint instability or repetitive strain in a particular area may be more prone to developing them.
Symptoms may include a noticeable lump on the foot, discomfort when walking, or difficulty wearing shoes. If the cyst is near a nerve, it may cause tingling, burning, or even sharp pain. Diagnosis typically involves a clinical exam. Your doctor may shine a light through the mass (transillumination) to determine if it’s fluid-filled, or aspirate (withdraw fluid from) the cyst for evaluation. In some cases, imaging such as X-rays or ultrasound may be recommended to rule out other causes or assess deeper structures.
