Oral Mucocele (Mucous Retention Cyst)

What Is a Mucocele?

Oral mucocele or mucous retention cyst, in other words, is a traumatic origin phenomenon that affects the salivary glands. A mucocele that affects the sublingual gland is a ranula. The mucoceles that are either extravasation or retentive are mainly due to obstruction, spillage, or blockage involved in the accessory salivary gland ducts.

What Are the Clinical Manifestations of Mucocele?

Discomfort, pain, and swelling in all areas result from the presence of a growing or a larger mucocele. Oral mucoceles are found most commonly in the oral cavity, with more than 70% of patients who are either young adolescents or children with a major prevalence below the 21-year range. The only exception to this prevalence is the ranulas, which may be simply put as oral mucocele occurring in either 30-50 years of age group or a retention mucocele commonly found in between 50 to 60 years of age group.

What Are the Causes of Mucocele?

Mucocele may arise from extravasation or retention of mucus with a diameter of 1 mm to as large as 2 cm. The pathogenesis of the extravasation cyst or mucocele may be due to the following etiologic factors:

1. Mechanical stress or friction to the gland (that results in a traumatic rupture of the salivary gland ducts).

2. Friction with an opposing tooth or with the oral mucosal layers or with the oral growth or of the inner cheek mucosa.

3. Tongue thrusting habit (tongue thrusting or exerting force against the surfaces of the teeth). This eventually causes a forceful exertion or build-up of the salivary gland secretions that in turn ruptures and spills its contents into the surrounding oral tissues. Fluctuation may be absent if the lesion has undergone some fibrosis or if the contents of the lesion are draining. A biopsy may be necessary to rule out malignancy if the dental or oral and maxillofacial surgeon suspects the feature but is not similar or consistent after examination with a simple oral mucocele.

How Is Mucocele Classified?

Based on the position of the cystic mucocele either within the mucosal surface and based on the pathology of the lesion, mucoceles are mainly categorized as below:

1. Superficial Mucocele: Cysts that are located beneath or below the mucosal surface lining.

2. Classic Mucocele: Cysts located above the upper layer of the submucosal layer.

3. Deep Mucocele: Cysts on the lower layers in the mucous membrane lining.

4. Extravasation Mucocele: This mucocele is amongst the most commonly occurring extravasation type and is caused by salivary gland duct secretions.

5. Retention Mucocele: This type of mucocele is caused due to the blockage of salivary gland ducts that is, pathophysiologically, mainly due to an absence of a defined decrease of glandular secretions produced by blockage of the salivary gland ducts. These mostly occur in older people aged between 50 and 60 years.

What Is the Difference between a Mucocele and a Ranula?

This is amongst the most common questions for a dental surgeon or practitioner and is crucial to diagnose and differentiate between a mucocele and a ranula. The ranula is also an oral mucocele of the sublingual gland; that is, it occurs in association with the submaxillary or sublingual gland ducts in the floor of the mouth specifically. Less often, it arises from the parotid duct (maxillary salivary gland duct). As its resemblance is similar to that of a bullfrog's throat, its terminology as a ranula came into existence. Hence technically, a ranula is an oral mucocele of the sublingual origin.

One more major difference between the pathogenesis of a ranula and mucocele is that, unlike the mucocele, the ranula is a very slow-growing painless mass that enlarges eventually overtime in the floor of the mouth. Ranulas can be further of a deep plunging sort wherein the ranula often herniates through the mylohyoid muscle and is called the cervical or deep plunging ranula. It is usually treated by marsupialization of the cystic content or the removal of the entire sublingual gland if it is recurring in nature.

How Is Mucocele Diagnosed?

1. Ultrasound evaluation is extremely valuable in most cases because the high fluid content of the cyst can be appreciated clearly through this technique.

2. If the origin and extent of the cyst need to be clearly appreciable and demarcated, CT or MRI scanning may help.

3. If a ranula has grown large and is encroaching into the muscles of the neck, then it may further require scanning.

4. Fine needle aspiration cytology (FNAC) with cellular analysis or chemical analysis can also give the diagnostic impression for a ranula. A fine-needle aspiration biopsy (FNAB) can also rule out other possible lesions (for differential diagnosis), especially if the color or size are atypical.

How Is Oral Mucocele Treated?

Considering that the pathology of trauma is typically responsible for initiating the blockage, spillage, or obstruction of the salivary glands, the management strategy does not vary much for both extravasation and retention of mucoceles. There is often a discharge of viscous fluid from the swelling following the build-up of cystic content. Hence the most common mode of removal for large or persistent lesions preferred method is surgical excision. This involves the removal of the cyst, the mucosa around it, and the glandular tissue until the muscular layer is reached, which is the procedure termed marsupialization (considered most effective surgically yet fails when the recurrence rate is high).

But if the mucocele exhibits recurrence, then the most successful surgical option is to remove the salivary gland source itself, especially in sublingual mucocele or ranulas. Surgical excision of the cyst or marsupialization is associated with a few complications, which include:

1. Recurrence if the lesion is not completely excised or removed.

2. Injury of the surrounding nerves, salivary glands, or salivary ducts, which may also lead to recurrence.

3. Hemorrhage.

4. Nerve injury.

In case of a ranula, apart from marsupialization treatment strategies so as to prevent fear and help with effective pain management in young adults and children suffering from mucocele, the following recent advanced techniques are highly recommended:

• Micro marsupialization.

• Cryosurgery.

• Intralesional corticosteroid injections.

• Electrocautery.

• Co2 laser ablation.

Conclusion:

To conclude, oral mucocele is a benign and commonly prevalent condition that can cause discomfort, swelling, and pain. Investigations, diagnosis by the maxillofacial surgeon or dentist, and painless surgical management only for large or persistent mucoceles to prevent recurrence of the lesions are useful in its management and to maintain oral health.

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