• Mucocele is a common lesion of the oral mucosa.
  • It’s a clinical term (based on the location of the lesion, clinical appearance, history given by patient etc.).

Mucocele on Lower Lip

Histo-pathologically Mucocele Is Of Two Types:-

Mucous Extravasation Cyst

  • Lesions in which mucus has extravasated into connective tissue from a severed excretory duct.
  • Mainly affect the minor salivary glands, particularly of the lip.
  • Not a TRUE CYST (no epithelial lining).

How Is A Mucous Extravasation Cyst Formed?

Normal Salivary Flow Phenomenon Vs How A Mucous Extravasation Cyst Is Formed

Clinical Features

  • Most common site is lower lip (as a result of injury or biting of mucosa).
  • Other sites:
    • Buccal mucosa
    • Floor of the mouth
    • Ventral tongue
    • Soft palate
    • Retromolar area
    • Upper lip is an uncommon site
  • Age – Children & young adults
  • Sex Predilection – Male = Female
  • Usually superficial
  • Size – Rarely larger than 1 cm in diameter
  • Appearance – Dome-shaped swellings, fluctuant, translucent bluish due to thin wall
  • Duration – Variable, Characteristic Finding: Alternate regression and recurrence due to the cystic cavity getting rupture and re-accumulation of saliva. Post rupture, they create painful ulcerations which heal within days.
  • Sometimes Superficial Mucocele (Variant) – Occur on soft palate, retromolar area, and posterior buccal mucosa and they appear as 1-4 mm tense vesicles that burst leaving behind painful ulcers. This should not be confused with vesiculo-bullous lesions.
  • A large mucocele in the floor of the mouth is called a Ranula

Histopathologic Features

Microscopically there is:-

  • Mucin Pool
  • Surrounded by Granulation Tissue Wall /compressed connective tissue wall in long standing lesions
  • No epithelial lining
  • Prominent cells Mucinophages – Macrophages migrate into the mucin pool and by phagocytosing it develop foamy or vacuolated cytoplasm
  • Sometimes – Ruptured salivary duct feeding into the area (called as Feeder Duct)
  • Adjacent minor salivary glands often contain chronic inflammatory cell infiltrate & dilated ducts

Treatment & Prognosis

  • Short-lived lesions rupture and heal by themselves
  • Long Standing – Surgical Excision along with adjacent minor salivary gland tissue
  • Prognosis is excellent, although sometimes may recur, especially if feeding glands not removed

Mucous Retention Cyst

  • Swelling due to obstruction of salivary gland excretory duct
  • Obstruction – salivary calculus/sialolith/salivary stone. Sometimes caused by periductal scarring or an impinging tumor
  • Accumulation of mucin within epithelial lined ductal cavity i.e. ductal dilatation secondary to obstruction
  • TRUE CYST – a retention cyst is lined by flattened/compressed ductal epithelium
  • Less common than mucous extravasation cyst

Clinical Features

  • Clinically difficult to differentiate from mucous extravasation cyst
  • Affects adults
  • SITE
    1. Major or minor salivary gland
    2. Intraoral Cysts commonly involve minor salivary glands of floor of mouth, buccal mucosa, lips
  • Pain especially at meal time

Histopathologic Features

  • Epithelial lining is variable
  • May consist of cuboidal , columnar, or atrophic squamous epithelium surrounding thin or mucoid secretions in the lumen
  • The epithelium may undergo oncocytic metaplasia appearing as papillary folds into the cystic lumen

Treatment

  • Surgical Excision along with adjacent minor salivary gland tissue

References

  • Shafer’s Textbook Of Oral Pathology
  • Shear – Cysts Of The Oral & Maxillofacial Regions
  • Neville – Oral & Maxillofacial Pathology
  • Image – Wikipedia & Wikimedia Commons