Primordial odontogenic tumor: A systematic review

Background: The primordial odontogenic tumor (POT) is a recently described benign entity with histopathological and immunohistochemical features suggesting its origin during early odontogenesis. Aim: To integrate the available data published on POT into a comprehensive analysis to better define its clinicopathological and molecular features. Material and Methods: An electronic systematic review was performed up to September 2019 in multiple databases. Results: A total of 13 publications were included, representing 16 reported cases and 3 molecular studies. The mean age of the affected patients was 11.6 years (range 2-19), with a slight predominance in males (56.25%). The posterior mandible was the main location (87.5%), with only two cases affecting the posterior maxilla. All cases appeared as a radiolucent lesion in close relationship to an unerupted tooth. Recurrences have not been reported to date. Microscopically, POT comprises fibromyxoid tissue with variable cellularity surrounded by a cuboidal to columnar odontogenic epithelium but without unequivocal dental hard tissue formation. A delicate fibrous capsule surrounds (at least partially) the tumor. The epithelial component shows immunohistochemical positivity for amelogenin, CK19, and CK14, and variable expression of Glut-1, Galectin-3 and Caveolin-1, Vimentin, p-53, PITX2, Bcl-2, Bax and Survivin; the mesenchymal tissue is positive for Vimentin, CD90, p-53, PITX2, Bcl-2, Bax, and Survivin, and the subepithelial region exhibits the strong expression of Syndecan-1 and CD34. The Ki-67 index is low (<5%). The negative or weak expression of dentinogenesis-associated genes could explain the inhibition of dentin and subsequent enamel formation in this neoplasm. Conclusion: POT is an entity with a well-defined clinicopathological, immunohistochemical and molecular profile that must be properly diagnosed and differentiated from other odontogenic lesions and treated consequently.