Why Do I Have a Lump in My Lower Lip?

A lump on the lower lip is referred to as a mucocoele, mucocele or mucous cyst, which is caused by saliva escaping the surrounding tissue and forming a fluid-filled lump, notes DermNet NZ. In most instances, a mucocoele forms on the lower lip but can also appear inside the mouth.

This lump, or mucous cyst, can range in size from 1 to 15 millimeters in diameter. The color of the mucous cyst can range from light pink to blue, depending on the size, according to DermNet NZ. The reason for this color difference deals with the epithelium, or outer layer, of the lip and the capillaries in that specific area. Capillaries are small blood vessels that support the cardiovascular system, explains InnerBody.