Primordial Odontogenic Tumor: A case report with histopathological analyses.

Primordial odontogenic tumor (POT) is a benign mixed epithelial and mesenchymal odontogenic tumor included into the current World Health Organization (WHO) classification of Head and Neck tumours in 2017. As far as the authors have confirmed, only eight cases of this tumor have been reported so far. This paper reports a case of POT that occurred in the right mandible of a 5-year-old patient. Panoramic radiograph showed a well-defined homogeneous radiolucency displacing the unerupted second deciduous molar to the deep part of the mandible. Histopathologically, the tumor was composed of cell-rich mesenchymal tissue with myxoid areas, surrounded by columnar epithelium and non-keratinized cuboidal epithelium in the outer layers. The histopathological diagnosis was POT. The expression patterns of cytokeratins (CK) 14, 18, 19, vimentin and CD34 suggested that the grade of differentiation of the POT was approximately equivalent to that of normal primary tooth germ tissues in cap stage to late bell stage.