Ganglion cysts are a noncancerous lump that are typically round or oval and are filled with a jellylike fluid. They most commonly develop along the tendons or joints of your wrists or hands but can also occur in the ankles and feet.
A plantar fibroma is a knot or nodule that is typically in the arch of the foot. This nodule is embedded in the plantar fascia. A plantar fibroma can happen on one or both of your feet at a time. Plantar fibromas are benign, but will not go away unless treated.