How common are mucous cysts, and why do they form? Mucous cysts, also known as mucoceles, are quite common in the general population, usually occurring on the lower lip.

Esho tells HuffPost that it’s important to remove the cysts, because “if the lip becomes infected or forms a foreign body reaction, the cyst can increase in size.” Shudder.

This can result in retention of mucus within the duct (mucous retention cyst) or, more commonly, the formation of a pseudocyst in the submucosa (mucous extravasation cyst). Differential diagnoses ...