A retention cyst, or a mucous cyst, is a thin cyst that contains clear fluid and grows on the inner portion of the lips. This kind of cyst is usually painless and may have a bluish color. A retention cyst can also develop on the floor of a person’s mouth as well as inside the cheeks, on the tongue or on the palate. People with pierced lips or a pierced tongue may notice this type of cyst around a pierced area.
Retention cysts can grow after an individual sucks the membranes of the lips between the teeth. In some cases, these cysts develop into a permanent bump on the inner part of the lips. Doctors often diagnose a cyst after visually examining the growths inside a patient’s mouth. A mucous cyst on the floor of the mouth may be called a ranula, and a cyst on the gums may be referred to as an epulis.
In many cases, a retention cyst goes away without treatment. Recurring cysts often need to be removed by a health care professional. A physician, dentist or oral surgeon may open the top of a cyst with a sterile needle to drain it, or they may surgically remove the growth.
Not all mouth sores are retention cysts. Cold sores may grow on the lips or inside the mouth due to a virus. White patches that grow inside the mouth could result from a yeast infection known as thrush. Leukoplakia is a disorder that causes excessive growth of cells inside the mouth that may appear as white patches.
A mucocele is related to a retention cyst and typically grows in the paranasal sinuses. This type of cyst is a lesion that develops in sinus passages that are congested with mucous. Mucoceles are trapped accumulations of mucous, and they may become infected in some cases. Doctors often use tests such as a computerized tomography, or CT, scan or magnetic resonance imaging (MRI) test to diagnose a mucocele.
People with past facial surgeries or facial traumas may have an increased risk of developing mucoceles. Some individuals with inflammatory diseases or allergies have a greater chance of having a mucocele grow inside their sinuses. This type of cyst may develop in men or women of any age.
In some instances, mucoceles cause headaches, facial pain or nasal obstruction. More serious symptoms, such as loss of vision and facial deformities, may occur with this kind of cyst. Sinuses can expand from excessive amounts of pressure that mucoceles exert on the inside of the sinuses. Physicians may treat mucoceles by draining them or surgically removing them.