A nasal vestibular cyst refers to a cystic mass located beneath the skin at the base of the nasal vestibule, anterior to the piriform aperture, and within the superficial soft tissue of the alveolar process of the maxilla. It is more commonly observed in females, typically between the ages of 30 and 50, with no significant difference between the right and left sides, though bilateral cases are occasionally reported.
Etiology
Glandular Retention Theory
This theory suggests that obstruction of the ducts of mucosal glands in the base of the nasal vestibule leads to the retention and gradual accumulation of glandular secretions, forming the cyst. For this reason, it is also referred to as a retention cyst.
Congenital Abnormalities
Some researchers propose that during embryonic development, residual or misplaced epithelial tissue at the junction of the maxillary process, globular process, and lateral nasal process may develop into a cyst, also known as a globulomaxillary cyst. However, this theory lacks sufficient evidence. The current understanding is that nasal vestibular cysts originate from remnants of the nasolacrimal duct. At 6 weeks of embryonic development, ectoderm in the groove between the lateral nasal process and the maxillary process invaginates to form the nasolacrimal groove, which later becomes the nasolacrimal duct. Epithelial remnants from this process can persist at the junction of the nasal ala and upper lip, serving as the basis for the formation of a nasal vestibular cyst.
Pathology
The outer wall of the cyst consists of connective tissue containing elastic fibers and reticular blood vessels, giving it a tough and elastic character. The cyst wall epithelium often includes ciliated columnar epithelium, cuboidal epithelium, or squamous epithelium, and it contains numerous goblet cells. The cystic fluid is typically yellow or brown and can be mucous or serous in nature. In cases of infection, the fluid becomes purulent, and the cyst wall shows inflammatory cell infiltration. Most cysts are round and vary in size. Adjacent bone tissue may be compressed and resorbed, forming a circular or disc-shaped depression.
Clinical Manifestations
The cyst develops slowly and is often unilateral. In its early stages, when the cyst is small, there are no noticeable symptoms. As the cyst enlarges, it can cause swelling at the site of attachment between the nasal vestibule and nasal ala on one side, accompanied by a sensation of distension and pain in the area of the nasal vestibule and upper lip, which may become more pronounced during chewing. Larger cysts that obstruct the nasal vestibule may lead to nasal obstruction on the affected side. In some cases, patients may experience referred pain in the maxillary or frontal regions. If the cyst becomes infected, it may enlarge rapidly, with increased localized pain.
Examinations and Diagnosis
Local Examinations
Swelling may be observed in the nasal vestibule, at the attachment of the nasal ala, or lateral to the piriform aperture on one side. In larger cysts, the nasolabial fold may appear shallow or absent. A palpable, raised, soft, and elastic mass—often compared to the consistency of a ping-pong ball—can be detected in the nasal vestibule or gingivolabial sulcus. Typically, the mass is not tender unless an infection is present. Aspiration of fluid can confirm the diagnosis, revealing a yellow, clear liquid. The cyst temporarily reduces in size after aspiration, but the swelling returns shortly after.
Imaging Studies
X-rays or CT scans may show hypodense, round or oval opacities at the base of the piriform aperture, with well-defined margins and no dental pathology. Surrounding bone compression and resorption may be noted.
Treatment
Surgical excision is the treatment of choice. Endoscopic surgery through the nasal cavity can be performed to remove the cyst’s top wall and create an opening in the nasal cavity floor, a procedure referred to as "marsupialization." Care is taken to prevent closure of the opening, which may result in recurrence. Complete cyst removal via endoscopic surgery is another option. Conventional surgery, involving a transverse incision in the gingivolabial sulcus and blunt dissection to excise the entire cyst wall, has been largely abandoned due to its invasive nature and associated trauma.