Nasopalatine duct cyst is a developmental non-odontogenic cyst caused by the entrapment of remnants during embryologic fusion. Only a few cases have reported the intraluminal amorphous calcification in these cysts. This case showed a well-demarcated, unilocular lesion containing calcifications, which were later turned out to be cartilage graft at previous surgery. We report here this case to emphasize the need for thorough medical history taking.

The trauma of incisive canal associated dental implant placement in the anterior maxilla can cause the nasopalatine duct cyst. It is difficult to identify the nasopalatine duct cyst or the location of the incisive canal, only using periapical radiograph or panorama radiograph. So it is necessary to take computed tomography scan for an analysis on the relation between the implant and the incisive canal. This case report present the patient had the nasopalatine duct cyst following the placement of dental implant in the anterior maxilla, and was undergone implant removal and cyst enucleation with bone graft.

The nasopalatine duct, the most dominant developmental tubule formed by the emergence of premaxilla and both sides of anterior palatal processes. This duct normally disappears in humans but remains latent and provides communication between the oral and nasal cavities in some mammals. However, the duct is obliterated and degenerated before birth in human, thus the persisting or patent nasopalatine duct in postnatal life is considered a developmental anomaly. Two cases of patent nasopalatine duct were presented in this study. Although the ducts were not sectioned longitudinally, they were probably connected each other and contained mucous materials secreted from the associated mucous glands. In the immunohistochemical study the ductal epithelium was consistently positive for the growth-related biomarkers including TGFβ1, c-erbB2, EGFR, CTGF, FGFb, HGF, eiF5A, FAK, and pAKT. And many columnar epithelial cells of the duct were positive for PCNA. Particularly, TNFα was clearly positive in the ductal epithelium together with β-defensin-2, -3 and MMP-3, -9. These findings may imply that the ducts have a growth potential postnatally and also can induce inflammatory reaction. Therefore, it was presumed that the present cases of patent nasopalatine ducts were caused by the latent proliferation of ductal epithelia in the vascular environment of nasopalatine canal without cyst formation, and also suggested that the patent nasopalatine ducts connected with functioning mucous glands were partly open to oral/nasal cavity and should be differentially diagnosed from the nasopalatine duct cyst.