Mucous cysts are classified into two types depending on the cause and the histopathological pattern. The first type is ‘mucous extravasation phenomena,’ or what is called a ‘mucocele.’ The other type is a mucous retention cyst [1]. Mucoceles represent cystic lesions resulting from mucus accumulation within the salivary glands. Although they commonly manifest in the minor salivary glands, the involvement of major salivary glands, particularly the submandibular gland, is relatively uncommon [2]. The term mucocele is derived from Latin word where “muco” means mucous and “cele” means cavity [3]. Mucocele is the most common salivary gland lesion in the oral cavity. They are most commonly found on the lower lip, lateral to the midline [4]. They are rarely seen on the upper lip, retro molar pad or palate. They may occur at any age, but are seen most frequently in the second and third decade of life. These lesions have no sex predilection [5].

Clinical appearance of both extravasation and retention mucoceles is similar. Mucoceles present as bluish, soft, and transparent cystic swelling that frequently resolve spontaneously. Blue colour is due to vascular congestion, cyanosis of the tissue above, and accumulation of fluid below. However, coloration may vary depending on the size of the lesion, proximity to the surface, and elasticity of overlying tissue [6].

Extravasation mucoceles appear frequently on the lower lip followed by the tongue, buccal mucosa, and palate and are rarely found in the retromolar region and posterior dorsal area of tongue; in contrast, retention mucoceles appear at any site in the oral cavity [7]. When located on the floor of the mouth, these lesions are called ranulas because the inflammation resembles the cheek of a frog [6].

Diagnosis of mucocele could be confirmed based on the lesion`s colour, site, etiology and consistency. Final diagnosis could be confirmed by histological investigations. Treatment modality for mucocele includes surgical excision, cryosurgery, laser excision, laser vaporization, marsupilization and micro marsupilization [8].

A 13 years old male child reported to the outpatient department of oral medicine and radiology with a chief complaint of painless swelling in lower right lip region since 3 months. The history of present illness consisted of swelling in inner aspect of lower lip since past 3 months. That was initially small and progressed to the present stage. Patient gives no history of pain and discharge. He also gave history of increase or decrease in size while mastication. The patient gave history of lip biting since 2 months. The patient had no history of difficulty in mastication and speech.

On palpatory clinical examination found that the lesion was soft, fluctuant and tenderness was absent. The lesion was approximately 5 × 3 cm in size. It was expanding inferiorly toward the lingual vestibule. The swelling was bluish pink in colour.

Figure 1: Intraoral View Showing Mucocele on the Lower Lip.

Routine blood investigation were done, and the value were in normal range. On the basis of the clinical features and habit history of lip biting the case was diagnosed as Mucocele. Treatment planning was done and explained to the patient’s guardian. After obtaining the parents’ consent treatment was performed included surgical excision on aseptic conditions under local anesthesia and Cauterization.

Management

Local anesthesia 0.8 ml Lidocaine with 1:100000 epinephrine, administrated through the local infiltration on the lower lip. The mucocele was excised by electro cautery. The specimen was placed in 10% formalin and sent for histo-pathological examination.

Figure 2&3: Intraoperative Photograph Showing Surgical Cauterization of Mucocele.

Histopathological examination revealed para-keratinized epithelium with few rete ridges. H&E stained section reveals pseudocystic cavity with extravasated mucin and the feeding minor salivary glands. The cystic cavity contains foamy histiocyctes, neutrophiles and granulation tissue. Large vascular spaces are also evident in surrounding connective tissue stroma. The lesion was confirmed as mucocele (extravasated type).

Figure 4&5: Confirmed the Diagnosis by Histopathological Examination (4x & 40x).

Surgically, various measures are taken to prevent recurrence such as complete excision of the lesion. During first few follow up visits; after 14 days, the wound healed by formation of granulation tissue. The patient was given post-operative instruction. The patient was asked not to touch the wounded area. Pain medications were prescribed (sos). The patient was asked to consume pain medications if he experienced pain.

 Figure 6: After 14 Days Follow Up.

Mucoceles are painless, asymptomatic swellings that have a relatively rapid onset and fluctuate in size. Mucoceles may be located either as a fluid filled vesicle or blister in the superficial mucosa or as a fluctuant nodule deep within the connective tissue. Spontaneous drainage of the inspisatted mucin especially in superficial lesions followed by subsequent recurrence may occur.⁹

The mechanism of formation of the mucocele is still not totally clear; however, a traumatic etiology rather than an obstructive phenomenon is favoured. Chaudhry et al showed that the escape of mucus into the surrounding tissue after severing the excretory salivary ducts lead to the formation of the mucocele. The most frequent occurrence of the mucocele in the lateral aspect of the lower lip, a trauma prone site. The present report also supports the role of trauma as an etiologic factor [11].

The incidence of mucoceles in the general population is 0.4–0.9%. There is no gender predilection. The appearance of mucocele is pathognomonic. Location of lesion, history of trauma, rapid appearance, variation in size, bluish colour, and the consistency, history, and clinical findings lead to the diagnosis of superficial mucocele. Lip contains adipose, connective tissue, blood vessels, nerves and salivary glands, and hence, pathology of any of these tissues can produce swelling on the lips. Mucocele, fibroma, lipoma, mucus retention cyst, sialolith, phlebolith, and salivary gland neoplasm appear as swelling on the lip. However, these can be distinguished from mucocele based on their clinical appearance, colour, consistency, etiology, and their location of occurrence [6].

Conventional surgical removal is the most common method used to treat this lesion. Other treatment options include CO2 laser ablation, cryosurgery, intralesional corticosteroid injection, micro marsupialization, marsupialization and electrocautery [11]. To reduce the chance of recurrence, lesion should be removed down to the muscle layer, all the surrounding glandular acini must be removed, and damage to the adjacent gland and duct should be avoided.

Mucocele are relatively common salivary gland cyst. Its recurrence rate is high. Because of high chances of recurrence, management of mucocele is a challenging task. However, surgical excision with dissection of surrounding and contributing minor salivary gland acini proved to be successful with least recurrence. Simple surgical excision is the treatment of choice, and when done with care, is the best treatment alternative.

Conflict of Interest: The authors declared that there is no conflict of interest.

Consent: Written informed consent was obtained from the patient for the publications of this case report and any accompanying images.

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