Overview and definition
The nasolabial cyst is a benign, nonodontogenic developmental cyst that arises exclusively in the soft tissues of the anterior midface, lateral to the nasal aperture and beneath the ala of the nose.[1][2] It is the only nonodontogenic cyst that occurs entirely within soft tissue rather than bone.[3] The prevailing pathogenetic theory holds that the cyst originates from epithelial remnants of the lower end of the nasolacrimal duct, supported by immunohistochemical profiling showing basal-cell expression of p63 and CK5/6 and luminal goblet-cell expression of MUC-2 and MUC-5AC mucins—a pattern consistent with distal nasolacrimal duct epithelium.[2][4] An older fissural-cyst theory, proposing origin from epithelium entrapped at the junction of the medial nasal, lateral nasal, and maxillary processes, is now largely disfavored because histopathologic findings do not consistently support it.[5][6] Because the cyst is extraosseous, conventional dental radiographs are characteristically normal or show only subtle secondary bony changes; cross-sectional imaging or ultrasonography is required for definitive radiologic identification.[5][7] Treatment is surgical, with excellent prognosis and very low recurrence.[1]
Terminology and classification
- Nasolabial cyst is the preferred topographic term, recommended because it avoids reference to disputed etiologic theories and variable histopathology.[5]
- Nasoalveolar cyst is a widely used synonym that emphasizes the relationship to the alveolar process; both terms are accepted interchangeably in the literature.[1][8]
- Klestadt's cyst (or Klestadt cyst) is an eponymous designation still encountered, particularly in European literature.[9][10]
- The lesion was historically classified among "fissural cysts," but this category has been abandoned in modern classifications because the fissural-entrapment theory of pathogenesis is no longer accepted for most entities previously placed in that group.[5][6]
- The lesion is classified as a nonodontogenic developmental cyst of the oral and maxillofacial region.[3][11]
Epidemiology
- Sex: Strong female predilection, with women representing approximately 75–92% of cases across large series.[1][3][12]
- Age: Peak presentation in the fourth and fifth decades of life, with a mean age at diagnosis of approximately 42–46 years.[1][3][13]
- Laterality: Usually unilateral. In a systematic review of 311 cases, left-sided lesions accounted for roughly 47%, right-sided for 38%, and bilateral cysts for approximately 11%.[1]
- Racial predilection: A higher reported prevalence among individuals of African descent has been noted in some series, though this observation is based on limited comparative data.[2][14]
- Frequency: Uncommon; the nasolabial cyst represents a small fraction of all maxillofacial cysts.[2][14]
Clinical presentation
Presentation and symptoms
The most common presenting complaint is a slowly enlarging, painless swelling in the nasolabial fold region, reported in approximately 71% of cases in a systematic review.[1] The swelling is located between the upper lip and the alar base, producing characteristic elevation of the nasal ala and obliteration of the nasolabial fold.[4][14] Intraorally, the lesion may present as a fluctuant, smooth, well-circumscribed mass in the labial vestibule above the apices of the maxillary incisors and canines.[4][15]
Additional symptoms
- Nasal obstruction: Common, resulting from medial displacement of the nasal floor and vestibular mucosa.[14][16]
- Pain: Typically absent unless secondary infection develops; localized pain or tenderness is reported in a substantial minority of cases.[14][16]
- Erythema: Overlying skin erythema is occasionally observed.[16]
Complications and mimics
Secondary infection occurs frequently and may mimic facial cellulitis, periodontal abscess, acute maxillary sinusitis, or nasal furuncle.[14] Infected cysts can present with acute pain, purulent drainage, and facial swelling, potentially leading to misdiagnosis.[14] The cyst is often unrecognized or confused with odontogenic pathology because of its proximity to the anterior teeth.[14]
Examination findings
Bimanual palpation—placing one finger in the nasal vestibule and one in the labial sulcus—reveals a smooth, fluctuant, compressible mass. Adjacent teeth are characteristically vital.[4][8] Aspiration yields mucoid or straw-colored fluid; however, simple aspiration invariably leads to recurrence and is not therapeutic.[14]
Radiographic findings
Because the nasolabial cyst is an extraosseous soft-tissue lesion, it is characteristically invisible or nearly invisible on conventional dental radiographs.[2][5] The radiographic section therefore addresses both the limited findings on intraoral projections and the more definitive features seen on cross-sectional imaging, including CBCT.
Location and distribution
- The cyst occupies the soft tissue lateral to the piriform aperture, beneath the ala nasi, above the alveolar process of the anterior maxilla, and superficial to the maxillary bone.[4][15]
- It extends posteriorly beneath the nasal floor toward the inferior meatus and anteriorly into the labio-gingival sulcus behind the upper lip.[15]
- The characteristic location is adjacent to the apices of the maxillary lateral incisor and canine, but the cyst does not arise from or involve these teeth.[4][8]
Conventional radiographic findings
- Periapical and panoramic radiographs: Typically unremarkable because the cyst is entirely within soft tissue. No intraosseous radiolucency is present unless long-standing pressure has produced secondary bone remodeling.[2][5]
- Anterior maxillary occlusal radiograph: May demonstrate the "distorted anchor" sign (Seward sign)—a posterior convexity of the radiopaque line forming the bony border of the nasal aperture on the affected side, caused by pressure remodeling from the adjacent cyst. A faint area of soft-tissue radiolucency may occasionally be superimposed over the anterior maxilla. This sign, while characteristic, is subtle and easily overlooked.[17]
Periphery and shape
- On cross-sectional imaging (CT or CBCT), the cyst appears as a well-defined, round to oval, homogeneous soft-tissue-density mass with smooth margins.[7][9]
- The lesion is encapsulated and does not demonstrate irregular or infiltrative borders.[2][4]
Internal architecture
- The internal content is homogeneously cystic (fluid density/signal), reflecting the mucoid secretions within the lumen.[7][18]
- No internal calcifications, septations, or solid components are present.[2][7]
- On CBCT, the cyst appears as a well-circumscribed, homogeneous soft-tissue-density structure in the expected anatomic location; the absence of internal mineralization or heterogeneity helps confirm the cystic nature.
Effects on adjacent structures
- Bone: The cyst is extraosseous but may produce smooth, pressure-type remodeling (scalloping or thinning) of the anterior face of the maxilla and the lateral margin of the piriform aperture. Frank bone destruction is not a feature; any bony change is secondary to chronic external pressure.[4][17]
- Teeth: Adjacent teeth remain vital and show no root resorption, displacement, or loss of lamina dura—a critical distinguishing feature from odontogenic cysts.[4][8]
- Nasal floor: The cyst commonly elevates and displaces the nasal floor mucosa medially, narrowing the ipsilateral nasal vestibule; this is well demonstrated on coronal cross-sectional images.[14][15]
Growth pattern and extent
- Slow, expansile growth within the soft tissue, with reported sizes ranging from approximately 1 cm to over 3 cm in greatest dimension.[7]
- Large cysts may extend to obliterate the nasolabial fold externally and efface the labial vestibule intraorally.[4][14]
Variants
- Bilateral cysts: Occur in approximately 11% of cases and should be specifically sought on imaging when one cyst is identified.[1]
Other imaging findings
CT (medical CT)
On contrast-enhanced CT, the nasolabial cyst appears as a well-circumscribed, homogeneous, low-attenuation (fluid-density) mass in the soft tissue lateral to the piriform aperture, with a thin enhancing wall.[1][7] CT was the most commonly employed imaging modality in a systematic review of 311 cases.[1] CT is superior to conventional radiography for demonstrating the extent of the lesion and its relationship to the maxillary bone, nasal floor, and nasal vestibule.[5] However, CT sensitivity for nasolabial cysts has been reported at approximately 80%, lower than ultrasonography, likely because small cysts may be overlooked when not specifically sought.[7]
MRI
MRI demonstrates the cyst as a well-defined mass with homogeneous intermediate signal intensity on T1-weighted images and homogeneous high signal intensity on T2-weighted images, consistent with simple fluid content.[9][18] MRI is considered superior to CT for delineating the relationship of the cyst to surrounding soft tissues and for confirming the accurate localization of the lesion.[9] On gadolinium-enhanced sequences, the cyst shows thin rim enhancement of the wall without internal solid enhancement, helping to exclude neoplastic processes.[18] Sagittal MRI may be particularly helpful for confirming the characteristic subalar location and distinguishing the nasolabial cyst from other spheric masses in this region, such as schwannoma.[19]
Ultrasonography
Transcutaneous ultrasonography reveals a well-defined, anechoic, oval cystic lesion in the anterior nasal floor region, with posterior acoustic enhancement.[7][20] Ultrasonography demonstrated the highest sensitivity (95%) and accuracy (95%) among imaging modalities in one comparative study and can serve as a simple, office-based first-line diagnostic tool.[7][20]
Differential diagnosis
The nasolabial cyst must be distinguished from other cystic and solid lesions presenting as swelling in the nasolabial region or anterior maxilla. The extraosseous location, vital adjacent teeth, and characteristic subalar position are the primary discriminating features.
| Entity | Why it is considered | Best discriminator |
|---|---|---|
| Periapical (radicular) cyst | Swelling in the anterior maxilla near tooth apices | Radicular cyst is intraosseous, associated with a nonvital tooth, and shows periapical radiolucency with loss of lamina dura; nasolabial cyst is extraosseous with vital teeth[4][8][14] |
| Nasopalatine duct cyst | Nonodontogenic cyst of the anterior maxilla that may present with palatal or labial swelling | Nasopalatine duct cyst is intraosseous and midline, centered on the incisive canal; nasolabial cyst is extraosseous and lateral to the piriform aperture[11][21] |
| Epidermoid or dermoid cyst | Soft-tissue cystic mass in the midface region | Dermoid/epidermoid cysts are lined by keratinized stratified squamous epithelium, may contain fat or skin adnexa, and lack respiratory-type epithelium with goblet cells[11][22][23] |
| Schwannoma of the nasal alar region | Spheric subalar mass mimicking nasolabial cyst clinically and on imaging | Schwannoma shows solid enhancement on MRI and heterogeneous signal, contrasting with the homogeneous cystic signal and rim-only enhancement of nasolabial cyst[19] |
The highest-risk diagnostic pitfall is misidentifying the nasolabial cyst as an odontogenic lesion (particularly a periapical abscess or cyst), which may lead to unnecessary endodontic treatment or extraction of vital teeth.[14] Vitality testing of adjacent teeth and recognition of the extraosseous location on cross-sectional imaging are essential to avoid this error.
Histopathology
Epithelial lining
The characteristic lining consists of pseudostratified columnar (respiratory-type) epithelium, which is the most common pattern.[3][8][24] The epithelium typically has a bilayered architecture: a basal layer of cuboidal cells and a luminal layer of tall columnar secretory cells with interspersed mucous goblet cells.[2][4]
Epithelial variants
- Stratified squamous epithelium: Commonly seen focally, either as areas of squamous metaplasia (particularly in inflamed cysts) or as the predominant lining in some cases.[8][24]
- Cuboidal epithelium: Occasionally observed as the sole lining type.[24]
- Mixed patterns: Combinations of respiratory, squamous, and cuboidal epithelium within the same cyst are common.[24]
Cyst wall
The fibrous connective tissue wall is composed of collagen-rich fibrovascular stroma with variably admixed chronic inflammatory cells.[2] Inflammation may be prominent in infected specimens.
Immunohistochemistry
- Basal cells express p63 and cytokeratin 5/6.[2][4]
- Goblet cells express MUC-2 and MUC-5AC mucins.[2]
- Proliferative activity (Ki-67) is characteristically low.[4]
- Podoplanin expression is discrete in non-inflamed areas but enhanced in zones of inflammation.[4]
Radiologic-pathologic correlation
The mucoid content produced by the secretory epithelium accounts for the homogeneous fluid density on CT and the high T2 signal on MRI. The thin fibrous capsule corresponds to the smooth, well-defined margins and thin rim enhancement seen on imaging. The absence of keratinization or solid components explains the lack of internal heterogeneity on all imaging modalities.
Management and prognosis
Surgical treatment
Complete surgical excision is the definitive treatment. Two principal approaches are established:
- Intraoral sublabial excision: The traditional standard approach, performed through a sublabial incision in the maxillary vestibule, allowing complete enucleation of the cyst. Breaches of the nasal vestibular mucosa during dissection typically heal spontaneously without repair.[1][24]
- Transnasal endoscopic marsupialization: An alternative approach in which the cyst roof (adherent to the anterior nasal floor mucosa) is excised transnasally, converting the cyst into an air-containing sinus that integrates into the nasal cavity. This technique can be performed under local anesthesia in an outpatient setting.[12][15]
A systematic review of 311 cases found similar efficacy and complication rates between the two approaches.[1] Newer techniques including transnasal Nd:YAG laser marsupialization and intranasal endoscopic microwave ablation have been reported with favorable short-term outcomes in small series.[16][25]
Complications
- The most common postoperative complication is transient facial or perinasal swelling.[1]
- Numbness of the upper lip or teeth occurs in a substantial proportion of cases and is usually temporary.[12]
- Oronasal fistula is rare.[16]
Recurrence
Recurrence after complete