Primordial odontogenic tumor (POT) is a recently designated benign mixed epithelial and mesenchymal odontogenic tumor and only sixteen cases have been reported worldwide till now. Here we report an another case of POT in a 14-year old boy who presented with an asymptomatic buccal enlargement in the right maxillary region for past 4-5 months. A well-defined, unilocular, radiolucent lesion with impacted teeth was observed radiographically. A detailed account of clinico-radiographical and histolological differential diagnoses along with an updated literature review has been presented.

BACKGROUND: A primordial odontogenic tumor (POT) is a rare, benign, mixed epithelial and mesenchymal odontogenic tumor that has been included as a new entity in the latest World Health Organization (WHO) classification (2017). POT consists of dental papilla-like myxoid connective tissue covered with a delicate membrane of ameloblastic epithelium. Only 15 cases have been documented worldwide, and here, we report the sixteenth case and the first one of South Korea.
METHODS: An asymptomatic lesion was discovered as an incidental radiographic finding in a 10-year-old boy. The patient had no complaints about the lesion. Cone-beam computerized tomograms revealed a round cavity with a defined cortical border measuring approximately 5 × 5 × 5 mm in size. The lesion was a POT. The patient was treated with enucleation. The tumor showed no recurrence for one year.
CONCLUSIONS: This is the first report of POT in South Korea using the novel diagnosis of POT after it was recognized and defined in the latest WHO classification. This novel diagnosis will be useful for pathologists and clinicians in diagnosing and differentiating this new and rare disease from other odontogenic tumors.

Primordial odontogenic tumor (POT) was recently recognized in the 2017 World Health Organization (WHO) Classification as a distinct mixed odontogenic tumor most commonly observed in the posterior mandible of young patients. POT appears as an expansile radiolucency associated to an unerupted tooth. The aim of the present study was to perform a retrospective microscopic evaluation of pediatric odontogenic tumors diagnosed in an Oral Pathology Laboratory from Rio de Janeiro-Brazil, in order to reclassify potential cases as POT. From 150 cases of odontogenic tumors in children diagnosed in the last 50 years, one case filled the criteria for POT, being therefore better diagnosed as such. The patient was in the first decade of life and presented a well-defined expansile tumor in the posterior mandible, which had been initially diagnosed as immature complex odontoma. To the best of our knowledge, only 12 cases of POT have been reported in the English-language literature. We herein present an additional case of POT and review of its clinicopathological findings is offered.

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.

Primordial odontogenic tumor (POT) is a rare lesion in the jaw which has been included as a new entity of benign mixed epithelial and mesenchymal odontogenic tumour in the latest World Health Organization (WHO) classification (2017). Only seven cases have been reported. It typically occurs in the posterior mandible. We report an additional case of POT in the maxilla of an 8-year-old girl presenting with an asymptomatic buccal enlargement. A well-defined, unilocular, radiolucent lesion was observed radiographically. Histologically, the tumor was mostly composed of loose fibrous connective tissue resembling dental papilla and a single layer of columnar epithelium covering the periphery of the tumor. In part, cords or nests of epithelium were present in the mesenchyme close to the periphery. Nestin, a marker of odontogenic ectomesenchyme, was positive in the mesenchymal tumor cells. We finally diagnosed the lesion as POT considering the possibility of other odontogenic tumors like ameloblastic fibroma or developing odontoma as a differential diagnosis. The patient shows no recurrence after 16 months. This case is the first report from Japan using this novel diagnosis POT after it was recognized and defined in the latest WHO classification.