Usually this type of lumps are found to be ganglions which bundle of neurones in the nerve root. There is as such no medical treatment for this condition it is not harmful and it is not painful either. It can be removed by surgery if wished for. However there is treatment in homeopathic medicine. There is no need to worry about it and sometimes it resolves by itself.

Your symptoms are suggestive of a ganglion cyst. Ganglion cysts are noncancerous lumps that most commonly develop along the tendons or joints of your wrists or hands. They also may occur in the ankles and feet. Ganglion cysts are typically round or oval and are filled with a jellylike fluid. Ganglion cysts can be painful if they press on a nearby nerve. Their location can sometimes interfere with joint movement. Since you don't have any difficulty it's better to leave it alone as it's shown to resolve on it's own. If you do develop pain or restriction of movements then I would advise you to visit a general surgeon so that it can be treated by immobilization, aspiration or by surgery.