Mucocele; Mucous retention cyst; Ranula; Epulis
Definition of Mucous cyst
A mucous cyst is a painless, thin sac on the inner surface of the lips. It contains clear fluid.
Causes, incidence, and risk factors
Mucous cysts are common. They are painless but can be bothersome because you are so aware of the bumps in your mouth. The cysts are thought to be caused by sucking the lip membranes between the teeth.
A thin, fluid-filled sac appears on the inside of the lip. The sac is bluish and clear. It is painless, but bothersome.
Signs and tests
Your doctor can usually diagnose a mucous cyst simply by looking at it.
A mucous cyst often can be left alone; it usually will rupture spontaneously. Opening the top of the sac with a sterile needle will help it go away. If the cyst returns, it may need to be removed.
Linda Vorvick, MD, Medical Director, MEDEX Northwest Division of Physician Assistant Studies, University of Washington School of Medicine. Also reviewed by David Zieve, MD, MHA, Medical Director, A.D.A.M., Inc. – 8/2/2009