A mucocele develops when a minor salivary gland duct is injured or severed and the salivary gland secretion spills into the adjacent connective tissue. Granulation tissue forms in response to the secreted mucus and comprises the lining of a cyst like structure. Unlike a true cyst, the cystic space is not lined by epithelium. The most common location is the lower lip. The mucocele is bluish in colour if located near the surface and normal in colour if deeper in the tissues. Some mucoceles are short-lived lesions that burst spontaneously, leaving shallow ulcers that heal within a few days. Many, however, require local surgical excision with removal of adjacent minor salivary glands to minimise risk of recurrence.