April 18, 2021
A mucocele is a swelling caused by the accumulation of fluid in a cavity or an organ. The word mucocele is formed by the confluence of two words - 'muco' meaning mucus and 'coele' meaning a cavity. As the name thus suggests, a mucocele is an abnormal formation of a cavity containing mucous. It can be seen in the appendix, gall bladder, nasal sinuses, but is most commonly seen in the mouth. An oral mucocele is a lesion that is usually associated with salivary glands.
Mucocele is the second most commonly occuring benign soft tissue mass of the oral cavity. This means that they are localized and do not have cancerous potential. They are associated with salivary glands, the structures responsible for secretion of saliva. Salivary glands are classified as major or minor depending on their size and the amount of salivary secretion. The salivary secretions are released through small openings called ducts. When these ducts are blocked as a result of trauma, infection or deleterious habits like lip biting and tongue thrusting, it hinders the flow of saliva, leading to the inflammation of the salivary gland. Poor oral hygiene can also be one of the facilitators of salivary duct blockage. The build-up of plaque can lead to the accumulation of bacteria which can in turn block the ducts.
The blockage of salivary ducts causes the saliva to leak into the surrounding soft tissues. This is commonly associated with minor salivary glands and is called extravasation cyst. When this phenomena takes place in major salivary glands, it is called a retention cyst. A mucocele's outer covering is called a pseudocapsule. Since mucocele commonly occurs on smooth surfaces like the lower lips and inner lining of the cheeks (buccal mucosa), the patient tends to bite the lesion, thereby rupture the pseudocapsule and cause repeated injuries at the site. This leads to the recurrence of the mucocele.
A dentist diagnoses a mucocele with proper history taking of the patient. Even though a definitive diagnosis is confirmed only through laboratory investigations, clinical diagnosis can be narrowed down by the patient's medical conditions, site of the mucocele and decoding the cause of the lesion. A mucocele can be firm or fluctuant in its consistency and has a pink or bluish tinge in its color. It rarely measures more than 1.5 cm and is asymptomatic.
Mucocele removal can be done in several ways. Some of them resolve on their own, while some others keep recurring if left untreated. These recurring lesions need to be excised along with the associated salivary gland. In some cases, the patient might be advised to rinse the mouth with salt water 4-5 times a day for a week. This can lead to the escape of the trapped fluid, thereby resolving the lesion.
Larger mucoceles can be resolved by corticosteroid injections. These drugs counter the inflammation and gradually regress the mucocele. Cryotherapy is another technique used to excise the mucocele. A cryotip or probe is used to inject nitrous oxide gas that is well below -20°C. The freezing cycles destroy the tissues and thus the mucocele. Electrocautery is also another treatment modality for mucocele removal. In complete contrast to cryotherapy, this technique employs temperatures as high as 2200°C to kill the cells. However, patient discomfort is seen more following an electorcautery and subsequent follow-ups can show a scarring around the healed tissues.
Minimally invasive techniques used more commonly today, especially in children are laser surgery and micro-marsupialization. The latter is less often used for oral mucoceles but has shown promising results. Micro-marsupialization involves incising the cyst, and suturing the borders of the incision. This forms a tract within the mucocele for the saliva to ooze out, thereby resolving the lesion. Laser surgeries with carbon-dioxide lasers, argon lasers or neodymium yttrium lasers have shown quick, painless and satisfying results. The treatment involves targeting a laser beam at the mucocele, while subsequently dissecting the underlying involved salivary gland. Post-operative follow-ups have shown promising healing of the tissues with better aesthetics compared to electrocautery.
Biopsies of the excised tissues are sent to the laboratory for the final diagnosis of mucocele. Ultrasound is also another investigation for diagnosing mucocele. Following the surgical procedure, the patient is supposed to be on an yearly follow-up for monitoring the healing of the tissues. The patient should also refrain from cheek or lip biting habits and is educated about maintaining proper oral hygiene. Mucoceles do not pose any threat, but need to be resolved through proper treatment planning if they persist over six weeks.