Aims: Odontogenic tumors are often biphasic, consisting of epithelial and interstitial components, with an origin that is not well understood. Odontogenic fibroma is rich in mesenchymal component, but also has many epithelial nests. We investigated the origin of this tumor by immunohistochemistry.
Methods: We investigated the expression of several odontogenic and epithelial markers including amelogenin by immunofluorescent studies.
Results: Immunohistochemical analysis demonstrated that epithelial nests exhibited E-cadherin expression, but not amelogenin. Amelogenin positive cells scattered in the fibrous tissue, which did not exhibit epithelial marker expression except for Epithelial Membrane Antigen (EMA). In one case that had received a test biopsy before whole resection of tumor, amelogenin positive cells were distributed in the regenerating mucosal epithelium or subepithelial tissue.
Conclusions: These results indicate that amelogenin positive cells of the odontogenic fibromas have an epithelial origin and may have the potential of epithelial mesenchymal transition (EMT), investigation of which has not yet started in benign tumors.