A noncancerous mucus-containing salivary gland cyst.
Lip biting and trauma to the face or mouth are common causes. Oral mucocele are seen most frequently in people younger than age 20.
The cysts often appear on the inside of the lower lip. They're typically painless and clear or bluish. Sizes vary.
Mucoceles often go away without treatment. However, removal of the salivary gland might be needed.