The primordial odontogenic tumor (POT) is a rare mixed odontogenic tumor composed of mesenchymal cells, columnar odontogenic epithelium, and fibromyxoid stroma affecting the posterior mandible of children and adolescents. Herein, we report 3 patients with POT and the clinicopathological features of POT previously reported in the literature. A 12-year-old, 19-year-old, and 4-year-old patient presented an asymptomatic swelling in the posterior maxilla and posterior mandible. Imaging exams revealed radiolucent lesions associated with unerupted teeth. The lesions were surgically removed, and the histopathological examination revealed spindle-to-ovoid mesenchymal cells in a fibromyxoid stroma surfaced by columnar odontogenic epithelial cells with reverse nuclear polarization. Deposition of mineralized tissue was observed. The final diagnosis was POT, and patients did not exhibit signs of recurrence. POT should be included in the differential diagnoses of intraosseous lesions in the posterior mandible in pediatric patients.

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.