Ganglion cysts are fluid-filled lumps that most commonly develop along the tendons or joints of wrists or hands. It looks like a water balloon on a stalk and contains a clear fluid or gelatinous material. Ganglion cysts are noncancerous, generally harmless and disappear without any treatment. However, if the cyst becomes painful or interferes with hand movement, they can be treated non surgically or removed surgically.