Squamous odontogenic tumor related to an unerupted lower canine.

A new case of squamous odontogenic tumor (SOT) is presented. This is the seventeenth case of SOT to be reported and the first reported case related to a lower unerupted canine. A review of the literature reveals the extreme variability of the clinical and radiologic features of this tumor. Conversely, the microscopic characteristics of SOT are clearly defined: numerous islands of benign squamous epithelium scattered in an apparently mature connective tissue, absence of peripheral columnar cells with palisading nuclei, and absence of stellate reticulum. Keratin pearl formation, intraepithelial microcyst formation, and calcification are present to a variable extent. A circular arrangement of fibroblasts and fibrous condensation and/or hyalinization are observed around some epithelial islands, suggesting a reaction of the connective tissue to the epithelial proliferation. The observation of small epithelial islands near the apical surface of the retained tooth supports the theory that the tumor originates from Malassez's rests. The treatment of choice seems to be conservative, with thorough enucleation, but it should be borne in mind that multifocal cases have been described.