Ranula

What causes a ranula

The sublingual glands sit under the floor of the mouth and continuously produce small amounts of saliva through several tiny ducts. If a gland or duct is damaged, saliva leaks into the surrounding tissue. The body walls it off with a lining of inflamed tissue, not a true cyst lining, which is why it is technically a "pseudocyst". Because the gland keeps producing saliva, the swelling keeps refilling.

Causes and associations:

• injury to the floor of the mouth, from biting, dental work or surgery
• blockage of the gland or duct
• often no identifiable cause
• plunging ranulas are more common in some populations, including people of Pacific Islander and Maori descent

Types

Symptoms

• a painless, soft, fluctuant swelling under the tongue, usually on one side
• a translucent or bluish color, said to resemble a frog's belly (hence "ranula", from the Latin for little frog)
• swelling that may burst, drain salty fluid, and refill
• with larger ranulas: tongue displacement, difficulty speaking, chewing or swallowing
• with plunging ranulas: a soft swelling under the jaw or in the neck
• rarely, breathing difficulty from very large lesions

Conditions that look similar

• mucoceles: smaller saliva-filled swellings, usually on the lower lip
• salivary gland stones: painful swelling under the jaw at mealtimes
• dermoid cysts: firmer, midline swellings in the floor of the mouth
• enlarged lymph nodes (lymphadenopathy), cystic hygromas (lymphatic malformations) and branchial cysts in the neck
• infections such as mumps (swelling of salivary glands) or abscess
• rarely, salivary gland tumors

Diagnosis

A dentist, oral surgeon or ENT specialist usually diagnoses a simple ranula by its appearance. For plunging ranulas or uncertain cases:

• Ultrasound: shows a fluid collection and its relation to the sublingual gland.
• MRI or CT: shows extension into the neck and helps plan surgery.
• Fluid aspiration: thick fluid high in salivary amylase supports the diagnosis.

Treatment

• Observation: small ranulas, especially in young children, sometimes resolve on their own.
• Removal of the sublingual gland (with the ranula): the most effective treatment, with the lowest recurrence rate, for both oral and plunging ranulas. It is done through the mouth under general anesthesia.
• Marsupialization: opening the ranula and stitching its edges to the mouth lining so it drains; simpler but with higher recurrence.
• Sclerotherapy: injecting a substance such as OK-432 to scar the cavity; used in some centers.
• Simple drainage or aspiration: usually followed by recurrence and generally not recommended alone.

After surgery, a soft diet is advised for a few days. Risks include temporary numbness of the tongue from irritation of the lingual nerve and, rarely, injury to the submandibular duct.

Outlook

Ranulas are benign. With removal of the sublingual gland, recurrence is uncommon. Losing one sublingual gland does not cause a noticeable dry mouth, because many other salivary glands remain.

Frequently asked questions

What is a ranula?

A ranula is a soft, fluid-filled swelling on the floor of the mouth caused by saliva leaking from a damaged sublingual gland. It is usually painless, bluish and on one side under the tongue. It is benign.

What is a plunging ranula?

A plunging ranula is a ranula that extends through the floor of the mouth muscles into the neck. It appears as a soft, painless swelling under the jaw or in the upper neck, sometimes with little or no visible swelling in the mouth.

Will a ranula go away on its own?

Small ranulas, particularly in young children, sometimes go away without treatment. Most persist or keep coming back, because the gland continues producing saliva. Removing the sublingual gland gives the best long-term result.

Is a ranula dangerous?

Ranulas are not cancerous and are usually harmless. Very large ones can interfere with speaking, eating or, rarely, breathing. Any swelling under the tongue or in the neck that persists should be examined to confirm the diagnosis.