Etiology: Mucoceles are caused by trauma and severance of an accessory salivary excretory duct. The damage to the ductal structure causes mucin to be retained in the sur- rounding tissue. The lesions related to the mucocele are discussed in more detail in Chapter 17 under salivary gland disorders. The mucocele is mentioned here because the lesion, depending upon the location and whether it is more superficial, may appear vesicle-like. The mucous retention cyst results from a sialolith, or salivary gland stone, and sometimes from ductal scar tissue, causing obstruction of the involved salivary gland. As stated previously, the fluids are retained within the structure of the cyst. Usually found in older adults, the mucous retention cyst is often found in the floor of the mouth. Figure 11.2 shows a mucous reten tion cyst in the floor of the mouth.