Mucocele

• Definition

  • Cystic lesions of minor salivary glands, that mostly appear in the lower labial mucosa, buccal mucosa or ventrum of tongue (Scully)
  • Mucocele is a clinical term that includes both mucus extravasation phenomenon and mucus retention cyst. Because each has a distinctive pathogenesis and microscopy, they are considered separately. Ranula is a clinical term that is used to describe a mucoele occurring in the floor of the mouth (Regezi)
  • MUCOCELE (MUCUS EXTRAVASATION PHENOMENON; MUCUS ESCAPE REACTION). The mucocele is a common lesion of the oral mucosa that results from rupture of a salivary gland duct and spillage of mucin into the surrounding soft tissues. This spillage is often the result of local trauma, although there is no known history of trauma in many cases. Unlike the salivary duct cyst (see page 457), the mucocele is not a true cyst because it lacks an epithelial lining. Some authors, however, have included true salivary duct cysts in their reported series of cases, sometimes under the classifi cation of retention mucocele Because these two entities exhibit distinctly different clinical and histopathologic features (Neville)
  • “Mucocele”is a clinical term that describes swelling caused by the accumulation of saliva at the site of a traumatized or obstructed minor salivary gland duct. Mucoceles are classified as extravasation types and retention types. A large form of mucocele located in the floor of the mouth is known as a ranula (Greenberg)
  • A mucocele is a cavity filled with mucus. Salivary mucoceles can be of two types, but these cannot be distinguished clinically and the difference is of little practical importance The most common type is the extravasation mucocele of minor glands, often called a mucous extravasation cyst even though it has no epithelial lining. The cause is trauma causing duct rupture so that saliva can escape into the tissues. Mucous extravasations most often form in the lower lip because it is more prone to trauma. They are commonest in children and young adults (Cawson)
  • The collection of secretion is superficial and rarely larger than 1 cm in diameter. In the early stages, they appear as rounded fleshy swellings. Later, they are obviously cystic, hemispherical, fluctuant and bluish due to the thin wall (Fig. 22.3). The saliva leaking into the surrounding tissues excites an inflammatory reaction (Figs 22.4 and 22.5), and the pools of saliva gradually coalesce to form a rounded collection of fluid, surrounded by compressed connective tissue. Gradually macrophages infiltrate and degrade the mucin, the duct heals and a scar remains. However, extravasation mucoceles often recur at the same site, probably because of recurrent trauma. In a superficial mucocele, the saliva pools just below the epithelium, mimicking a vesicle and potentially presenting similarly to pemphigoid. The translucent blisters are a few millimetres in diameter and usually affect the soft palate (Cawson, 2023)

  

• Prevalensi

  Mucoceles typically appear as dome-shaped mucosal swellings that can range from 1 or 2 mm to several centimeters in size (Figs. 11-2 to 11-4). They are most common in children and young adults, perhaps because younger people are more likely to experience trauma that induces mucin spillage. However, mucoceles have been reported in patients of all ages, including infants and older adults. (Neville)

• Gambaran klinis

  • Mucoceles are fluctuant bluish lesions mostly caused by trauma to the duct, leading to mucous extravasation (extravasation mucoceles). This type of mucocele is not, however, lined by epithelium, and, therefore, is not a true cyst (Scully)
  • Mucoceles typically appear as dome-shaped mucosal swellings that can range from 1 or 2 mm to several centimeters in size (Figs. 11-2 to 11-4). They are most common in children and young adults, perhaps because younger people are more likely to experience trauma that induces mucin spillage. However, mucoceles have been reported in patients of all ages, including infants and older adults.

• Etiology and Pathogenesis

  • Occasional mucoceles are caused by saliva retention ( retention mucoceles), especially in the floor of mouth when they may resemble a frog belly and are termed ‘ranula’(Scully)

  • The cause of mucus extravasation phenomenon is traumatic severance of a salivary gland excretory duct, resulting in the escape of mucus, or extravasation, into the surrounding connective tissue (Figure 8-1). An inflammatory reaction of neutrophils followed by the accumulation of macrophages ensues. Granulation tissue forms a wall around the mucin pool, and the associated salivary gland undergoes inflammatory change. Ultimately, scarring occurs in and around the gland (Regezi)

    

  • The spilled mucin below the mucosal surface often imparts a bluish translucent hue to the swelling, although deeper mucoceles may be normal in color. The lesion characteristically is fl uctuant, but some mucoceles feel fi rmer to palpation. The reported duration of the lesion can vary from a few days to several years; most patients report that the lesion has been present for several weeks. Many patients relate a history of a recurrent swelling that periodically may rupture and release its fl uid contents. The lower lip is by far the most common site for the mucocele. However, one interesting variant, the superfi cial mucocele, does develop in these areas and along the posterior buccal mucosa. Superfi cial mucoceles present as single or multiple tense vesicles that measure 1 to 4 mm in diameter (Fig. 11-5). The lesions often burst, leaving shallow, painful ulcers that heal within a few days. Repeated episodes at the same location are not unusual. Some patients relate the development of the lesions to mealtimes. Superfi cial mucoceles also have been reported to occur in association with lichenoid disorders, such as lichen planus, lichenoid drug eruptions, and chronic graftversus-host disease (GVHD). The vesicular appearance is created by the superfi cial nature of the mucin spillage, which causes a separation of the epithelium from the connective tissue. The pathologist must be aware of this lesion and should not mistake it microscopically for a vesiculobullous disorder, especially mucous membrane (cicatricial) pemphigoid.

  • The formation of an extravasation mucocele is believed to be the result of trauma to a minor salivary gland excretory duct. Laceration of the duct results in the pooling of saliva in the adjacent submucosal tissue and consequent swelling. The extravasation type of mucocele is more common than the retention form. Although often termed a cyst, the extravasation mucocele does not have an epithelial cyst wall or a distinct border. In contrast, the retention mucocele is caused by obstruction of a minor salivary gland duct by calculus or possibly by the contraction of scar tissue (Greenberg)

• Miscroscpic exam/ HPA

  • Extravasation of mucin into the connective tissues incites an inflammatory response with neutrophils, macrophages, and granulation tissue forming around the mucin pool (Figure 8-4). The adjacent salivary gland whose duct was transected shows duct dilation, chronic inflammation, acinar degeneration, and interstitial fibrosis. (Regezi)

  

  • On microscopic examination, the mucocele shows an area of spilled mucin surrounded by a granulation tissue response (Figs. 11-6 and 11-7). The infl amma tion usually includes numerous foamy histiocytes (macrophages). In some cases a ruptured salivary duct may be identifi ed feeding into the area. The adjacent minor salivary glands often contain a chronic infl ammatory cell infi ltrate and dilated ducts (NEville)

  

• DD

  Mucoceles are diagnosed clinically but it is important to differentiate from a cystic neoplasm, this being most likely in the upper lip ( usually a canalicular adenoma) (Scully)

• Tx

  Most mucoceles either resolve spontaneously or can be excised, ligated or removed with cryosurgery (Scully)

  • Some mucoceles are short-lived lesions that rupture and heal by themselves. Many lesions, however, are chronic in nature, and local surgical excision is neces sary. To minimize the risk of recurrence, the surgeon should remove any adjacent minor salivary glands that may be feeding into the lesion when the area is excised. The excised tissue should be submitted for microscopic examination to confi rm the diagnosis and rule out the possibility of a salivary gland tumor. The prognosis is excellent, although occasional mucoceles will recur, necessitating reexcision, especially if the feeding glands are not removed (Neville)
  • The treatment of choice for mucoceles is surgical excision. Removal of the associated salivary glands is essential to prevent recurrence. Aspiration of the fluid only does not provide long-term benefit. Managing of mucoceles can be difficult because surgical removal may cause trauma to other adjacent minor salivary glands and lead to the development of a new mucocele. Intralesional injections of corticosteroids have been used successfully to treat mucoceles (Greenberg)