Nasopalatine Duct Cyst

Nasopalatine duct cyst, also called incisive canal cyst, is the commonest non-odontogenic developmental cyst of the jaws. It arises in the incisive canal or the incisive papilla in the anterior midline of the palate.

It accounts for roughly 70% of non-odontogenic jaw cysts and for 1 to 1.5% of jaw cysts overall. It presents most often in the fourth to sixth decades, with men more affected than women.

Pathophysiology. The cyst comes from remnants of the epithelium of the nasopalatine duct, which links the oral and nasal cavities in the embryo. Stimuli such as trauma, infection or mucous secretion probably start the cyst.

It grows slowly by fluid accumulation, and the wall often contains nerves and vessels of the neurovascular bundle of the canal.

Many have no symptoms. Others notice a swelling of the anterior palate behind the incisors, a salty or purulent discharge, pain from denture pressure, and nasal obstruction or a nasal swelling. The adjacent teeth are vital, with divergent roots when the cyst is large.

Pain and discharge suggest infection. A fixed, ulcerated or fast growing lesion needs biopsy to exclude other disease.

• Periapical or occlusal radiograph: a round, oval or heart shaped, well corticated radiolucency between the roots of the upper central incisors, with a canal width over 6 mm suggesting a cyst.
• Cone beam CT: shows the canal expansion, relation to the nasal floor and roots, and helps planning.
• Pulp sensibility tests: the adjacent teeth respond normally. A non-vital incisor suggests a radicular cyst instead.
• Aspiration: yellow straw fluid, sometimes with cholesterol crystals.
• Histology of the whole lesion: stratified squamous, pseudostratified columnar or cuboidal epithelium, often mixed, with nerves, vessels and mucous glands in the wall.

Differential diagnosis.

• Radicular cyst of an upper central incisor
• Enlarged incisive foramen (normal variant)
• Median palatal cyst
• Odontogenic keratocyst
• Nasolabial cyst
• Periapical granuloma
• Palatal abscess and minor salivary gland tumour
• Neoplasm of the nasal cavity or palate

• Asymptomatic small cysts with an uncertain diagnosis can be observed, with radiographic review at 6 months and annually.
• Symptomatic or enlarging cysts: enucleation through a palatal flap, with care to preserve the nasopalatine neurovascular bundle where possible, accepting numbness of the anterior palate. A labial approach is an alternative, especially with a large cyst or an associated apical lesion.
• Large cysts extending to the nasal cavity: enucleation with a surgical approach combined with marsupialisation in selected patients.
• Send tissue for histology. Recurrence is uncommon, at about 2 to 3%.
• Antibiotics only for infection: amoxicillin 500 mg orally three times daily for 5 days (reduce to 500 mg every 12 hours at eGFR 10 to 30), or clindamycin 300 mg four times daily in penicillin allergy.
• Analgesia: paracetamol 1 g every 6 hours (maximum 4 g daily) with ibuprofen 400 mg every 8 hours with food.

Monitoring. Radiographs at 6 and 12 months, then annually for 2 years after surgery. Check for anterior palatal numbness and healing of the flap.

Referral and escalation. Refer to oral and maxillofacial surgery for planning. Urgent referral for rapid growth, ulceration, nasal obstruction or histology that is not typical.