A mucous cyst is a painless, thin sac on the inner surface of the lips. It contains clear fluid.
Mucocele; Mucous retention cyst; Ranula; Epulis
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.
Mucous cysts are harmless. If left untreated, however, they can organize and form a permanent bump on the inner surface of the lip.
They are called ranula when on the floor of the mouth, and epulis when on the gums.
The sac may form around jewelry (piercings) that has been inserted into the lips or tongue.
A thin, fluid-filled sac appears on the inside of the lip. The sac is bluish and clear. It is painless, but bothersome.
The sac can also occur on the tongue, palate, inside the cheeks, the floor of the mouth, or around tongue or lip piercings.
Signs and tests
Your health care provider 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.
To prevent infection and damage to the tissue, opening the sac should NOT be performed at home by the parents. This should be performed by your health care provider. Oral surgeons and some dentists can easily remove the sacs if they continue to be uncomfortable.
There are usually no complications.
Calling your health care provider
If it becomes uncomfortable, have the cyst examined by your health care provider during a routine examination.
There is no known prevention. Avoid intentionally sucking the cheeks or lips between the teeth.
Morelli JG. Disorders of the mucous membranes. In: Kliegman RM, Behrman RE, Jenson HB, Stanton BF, eds. Nelson Textbook of Pediatrics. 19th ed. Philadelphia, Pa: Saunders Elsevier; 2011:chap 656.
Daniels TE. Diseases of the mouth and salivary glands. In: Goldman L, Ausiello D, eds. Cecil Medicine. 24th ed. Philadelphia, Pa: Saunders Elsevier; 2011:chap 433.
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.