Adenomatoid odontogenic tumor (AOT) is a relatively rare benign tumor, accounting for 2% to 7% of odontogenic tumors. AOT is generaly found in the incisor region of the maxilla of young females. It is often misdiagnosed as dentigerous cyst. We report a case of AOT found in the third molar region of the mandible. The patient was a 17-year-old girl who was referred for further evaluation of a cystic radiolucent lesion of the mandible.
We diagnosed a dentigerous cyst because the X-ray film and CT examination showed a monolocular radiolucent lesion including an impacted tooth with no calcification. We enucleated the tumor and the impacted lower third molar with the patient under general anesthesia. Histological examination revealed an adenomatoid odontogenic tumor with duct-like structures lined by a single layer of columnar epithelial cells. There was proliferation of spindle-shaped cells, but no clear evidence of typical calcification. There has been no sign of recurrence as of 4 years after the operation.
