Ephelis

Epulis or a mucous retention cyst can be described as a bluish, thin sac over the inner surface of the lips that contain clear fluid. Also referred to as Mucocele, Epulis are very common. Though they are painless, but can be irritating for you can feel the bumps inside your mouth, caused by sucking of the lip membranes between the teeth. If not treated on time, they may become permanent bumps on the inner surface of the lips. If they form on the base of the mouth, they are known as ranula, and if on the gums, they are called epulis.