Abstract
Adenomatoid odontogenic tumor （AOT） is classified as a rare, benign odontogenic tumor. AOT is more commonly developed in the maxilla with an impacted tooth. In this study, we described a rare case of AOT developed in the mandible without an impacted tooth. A 25-year-old Japanese female had been aware of gum swelling affecting the mandibular premolar region. Due to the development of the gum swelling, she was referred to our hospital for clinical attention. At the initial visit to our hospital, the swelling in the buccal gingiva at the left lower canine and first premolar region was not associated with any pain. Panoramic X-ray and CT exhibited absence of any impacted tooth and a 12×10×10mm-well-circumscribed radiolucent mass with points like radiopacity at the inter-radicular area between the left mandibular canine and the first premolar. Initial clinical diagnosis of the case was a mandibular benign tumor, and it was conservatively treated by surgical enucleation and curettage. Moreover, histopathological findings showed nodules with a columnar epithelium with variably sized rosette- or duct-like spaces. Around these duct-like spaces are small foci of calcification. Thus, we finally diagnosed this lesion as adenomatoid odontogenic tumor. There were no signs of recurrence for 2 years after the procedure. Cases of AOT with no impacted tooth are defined as extrafollicular variant, and only few cases have been reported of this variant. More knowledge about extrafollicular variant of AOT needs to be explored. Although recurrence rates of AOT are exceedingly low, careful and sustained follow-up is still highly recommended.
