Mucocele represents a condition in which damage to one of the small salivary (spit) glands leads to the formation of a soft bump or a blister-like lesion in the mouth. This can occur on lips, under the tongue, or less commonly on the roof of the mouth. It is a common and harmless phenomenon, although it can be annoying for the patient.
Mucocele is probably caused by minor injury to the little tube, called a duct, that carries saliva from the salivary gland onto the surface of the mouth. The injury can be caused due to accidental trauma such as biting. When the injury occurs, the thick, mucus-type saliva produced by the damaged gland is released into the surrounding tissues instead of going into the mouth with the rest of the saliva. This often creates a clear or bluish bubble or blister. If the blister is poked at or further injured, bleeding can occur within the entrapped pool of saliva that would make it look red or purple.
A history of enlargement, breaking, and shrinkage is fairly common, and these lesions can be remarkably persistent. If untreated, these will often swell, break (like a water balloon), and heal over, only to swell again and repeat the cycle. This condition rarely goes away on its own. An oral surgeon usually has to remove the spilled saliva and affected gland in order to completely stop the process, but this is a rather minor procedure. The excised tissue should then be examined under the microscope to exclude the very small chance of some form of growth or tumor.
For more information:
Go to the Mouth Diseases health topic.