After transnasal marsupialisation

Therapeutic intervention: A diagnosis of the nasolabial cyst was made and nasal marsupialisation excision via sub labial approach under local anaesthesia was successfully done.

Follow-up and outcomes: No postoperative complications were seen and no lesion recurrence was noted after 12 months of follow up.

DISCUSSION

Nasolabial cyst in an uncommon lesion located near the alar cartilage extending into the superior nasolabial groove and the floor of the nasal vestibule. It is classified as a non-odontogenic, extra osseous cyst and is usually located in the area of the nasolabial sulcus, just below the ala nasi. It accounts for approximately 7% of maxillary cysts and is unilateral in 90% of cases and bilateral lesions have been reported in the literature. It represents about 0.7% of all cysts in the maxillofacial region and 2.5% of non-odontogenic cysts [2,3].

This case illustrates the classical clinical presentation of a nasolabial cyst. The clinical features described in many publications were observed in this case especially the effacement of the nasolabial sulcus and the elevation of the ala nasi. According to the literature some patients can be asymptomatic but most have at least one of the three following partial or complete nasal blockage, well-circumscribed swelling and local pain (all were found on our patient). Nevertheless, in order to appreciate the extension of the lesion and the bone erosion, CT scan and MRI were not done due to unavailability in our town and financial constraints. It was also difficult to compare our data to others because the published data about the same condition are not easily available.

Pathogenesis

The pathogenesis of nasolabial cysts is still uncertain. Two theories have been suggested to explain the origin of nasolabial cyst:

1.       Klestadt in 1913 suggested that they arise from trapped epithelium at the point where the maxillary, medial nasal and lateral nasal processes fuse which become inclusion cyst (fissural cyst). However, a lack of evidence to support the idea of embryonic epithelial entrapment in this location prompted many researchers to discard this hypothesis.

2.       Bruggeman in 1920 had suggested that nasolabial cysts develop from remnants of the embryonic nasolacrimal ducts (developmental cyst). This theory is supported by the fact that the nasolacrimal ducts are lined with pseudostratified columnar epithelium, which is the type of epithelium found in the nasolabial cyst cavity. Currently, it is the most widely accepted theory [4].

Diagnosis

Symptoms and signs: The nasolabial cyst is usually asymptomatic. The patient presents only when the cyst becomes infected or when it causes unilateral fullness in the nasolabial region. Patients initially noticed a fullness in the nasolabial region before it becomes symptomatic. Due to the particular presentation and location of these lesions, their diagnosis is almost exclusively clinical. The most common sign is enlargement causing facial asymmetry due to the displacement of the upper lip, with an elevation of the ala nasi and effacement of the nasolabial sulcus. Local pain, nasal obstruction, and concomitant infection which can lead to abrupt enlargement of the lesion may also be present. Occasionally in late presentation, it can present with nasal obstruction when it pushes on the inferior turbinate causing it to medialize [1-3].

On inspection, nasolabial cyst appears to be either normal pink or bluish in color. The cyst is best palpated bimanually with a finger in the floor of the nose and other in the labial sulcus. The cyst appears underneath the ala nasi as a painless fluctuant swelling extending laterally into the cheeks, often obliterating the nasolabial sulcus, and extending anteriorly into the lip and mucobuccal vestibule [2,3].

Imaging: Periapical radiographs, nasolabial cysts may present as a radiolucent area in the apical region of the maxillary incisors. Standard occlusal views show posterior displacement of the radiopaque line corresponding to the bony margins of the anterior nasal aperture.

In the absence of radiographic findings and when a more precise analysis of the borders of the lesion is required, CT SCAN is the imaging modality of choice. CT scans usually reveal a homogeneous, well-delimited cystic lesion in the lateral nasal region cystic lesion, with no contrast uptake. Larger lesions may be associated with bone remodeling of the underlying maxilla. CT is able to demonstrate soft tissue nature as well as bony involvement. As the cyst is benign there is no bony erosion other than expansible lesion causing thinning of the bone [5].

Ultrasonography does not offer much other than to reveal the cystic nature of these lesions, for example, well circumscribed, rounded or oval shapes and anechoic fluid-filled masses in the nasolabial sulcus region [5,6]. Magnetic Resonance Imaging (MRI) shows the characteristics of the fluid in T1 (low intense) and T2 (bright) views [2,5].

Histopathology

Histopathological examination reveals ciliated pseudostratified columnar epithelium and occasionally, stratified squamous epithelium. In a scanning electron microscopy study of the inner surface of nasolabial cysts, non-ciliated columnar epithelium with basal cells and goblet cells is found [3,4].

Differential diagnosis

Differential diagnosis of the nasolabial cyst includes:

a.       Odontogenic cyst: It originates from tissues involved in tooth development. So careful examination will show evidence of non-vital tooth with radiolucency.

b.       Dentigerous cyst: most common sites are mandibular third molar and maxillary third molar, large cysts tend to expand the outer plate (usually buccally).

c.        Dermoid or epidermoid cyst: As opposed to the normal pink or bluish coloration of a nasolabial cyst, this cyst is yellow in color.

d.       Fibrous-osseous disease: Painful, hard, bone is replaced by fibrous tissue [3,7].

TREATMENT

Treatment is aimed to prevent infection, to improve a cosmetic deformity and to establish a histopathological diagnosis.

The current treatment of nasolabial cyst is complete excision:

a.       Surgical enucleation is easily achieved via a transoral sublabial approach.

b.       Transnasal marsupialisation of the nasolabial cyst which opens into the nasal cavity has reported no recurrence of the cyst. It is the technique applied to our patient. It is 12 months since the excision was done no recurrence has been reported [8].

c.        Recently, the alternative transnasal route was proposed by some authors: Endoscopic approach extends the nasal floor to the former cystic cavity and thus prepares an air-containing sinus. This technique appears to allow sufficient drainage of the new sinus and there were no signs of cyst recurrence [9-11].

d.       Other modes of treatment that had been described are simple aspiration, injections with a sclerosing agent, destruction by cautery, needle aspiration and incision and drainage. However, these methods have been found associated with high recurrence rates [8,11].

CONCLUSION

From the literature and the present case, the diagnosis is based on clinical findings. Despite the rarity of the nasolabial cyst, the general practitioners, ENT specialists and dental practitioners should recognize the key features of these lesions in order to be able to distinguish them from the odontogenic origin and enable appropriate treatment. Therefore, a diagnostic hypothesis of nasolabial cyst should be based on clinical examination and imaging; and histopathology is necessary to confirm the diagnosis. CT and MRI are good to make a diagnosis but clinical examination can be enough to get a diagnosis of nasolabial cyst in poor settings. Once the diagnosis is established, the optimal treatment consists of complete excision using sophisticated equipment but nasal marsupialisation can guarantee good prognosis and rare recurrences.

DECLARATIONS

Ethics approval and consent to participate

Not applicable

Consent for publication

Written informed consent for publication of his clinical details and clinical images was obtained from the patient.

Availability of data and materials

The datasets used and analyzed during the current study are available from the corresponding author on reasonable request.

Competing interests

The authors declare that they have no conflicts of interest.

Funding

This study received no financial support.

Acknowledgement

We are grateful to Dr. Jeef Mutambala, Mrs Namushukuru Yvette and Mbindule Eugénie for helpful advice regarding data collecting and assist in the preparation of the manuscript.

Author’s contributions

1.       Nzanzu Kikuhe collected the data and wrote the initial draft of the manuscript. He also performed the operation and collected the data.

2.       Sekabuhoro Safari was involved in the preoperative and postoperative evaluation of the patient.

3.       Munyaneza Sekimonyo Claude was involved in the preoperative and postoperative evaluation of the patient.

4.       Emily Kakande contributed to analysis and interpretation of the data.

5.       Justine Namwagala reviewed the final manuscript.