Ranula

A ranula is a type of mucocele found on the floor of the mouth. Ranulas present as a swelling of connective tissue consisting of collected mucin from a ruptured salivary gland duct, which is usually caused by local trauma.
The Latin rana means frog, and a ranula is so named because its appearance is sometimes compared to a frog's underbelly.

 ETIOLOGY :

Ranulas

Congenital ranulas can arise secondary to an imperforate salivary duct or ostial adhesion. These are very rare and have been known to spontaneously resolve.
Posttraumatic ranulas arise from trauma to the sublingual gland, leading to mucus extravasation and formation of a pseudocyst. The more appropriate term for this may be mucus escape reaction (MER).

Pathophysiology

Ranulas are formed from 1 of 2 processes:

• Partial obstruction of a sublingual duct can lead to formation of an epithelial-lined retention cyst. This is unusual, occurring in less than 10% of all ranulas.
• Trauma can lead to formation of ranulas. Experimentally, partial severance or ligation of the sublingual duct leads to ranula formation, whereas ligation of the submandibular duct does not. The ligation of the parotid duct ultimately leads to atrophy. The difference lies in the fact that the sublingual gland secretes continuously in the interdigestive period, whereas the other two major salivary glands only secrete in response to stimuli, such as eating. Therefore, with trauma, if a duct is obstructed, secretory backpressure builds and acini rupture, leading to mucus extravasation. Alternately, trauma causes direct damage to the duct or acini, leading to mucus extravasation. A pseudocyst then forms.

Representation :
A ranula is most commonly observed as a bluish cyst located below the tongue as seen in the images below. It may fill the mouth and raise the tongue. Typically, these are painless masses that do not change in size in response to chewing,

Causes, incidence, and risk factors

Mucous cysts are common. They are painless but can be bothersome because you are so aware of the bumps in your mouth. The cysts are thought to be caused by sucking the lip membranes between the teeth.
Mucous cysts are harmless. If left untreated, however, they can organize and form a permanent bump on the inner surface of the lip.
They are called ranula when on the floor of the mouth, and epulis when on the gums.
The sac may form around jewelry (piercings) that has been inserted into the lips or tongue.

                                                              CT SCAN

Symptoms

A thin, fluid-filled sac appears on the inside of the lip. The sac is bluish and clear. It is painless, but bothersome.
The sac can also occur on the tongue, palate, inside the cheeks, the floor of the mouth, or around tongue or lip piercings.

Signs and tests

Your health care provider can usually diagnose a mucous cyst simply by looking at it.

Treatment

A mucous cyst often can be left alone; it usually will rupture spontaneously. Opening the top of the sac with a sterile needle will help it go away. If the cyst returns, it may need to be removed.
To prevent infection and damage to the tissue, opening the sac should NOT be performed at home by the parents. This should be performed by your health care provider. Oral surgeons and some dentists can easily remove the sacs if they continue to be uncomfortable.