MUCOCELE – All You Need To Know

• 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.)

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?

CLINICAL FEATURES

• SITE:-
  • 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 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 floor of mouth is called as 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

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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
  • Major or minor salivary gland
  • 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

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REFERENCES

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