Comparative Immunohistochemical Study of Tooth Germ and Primordial Odontogenic Tumor

Objectives: The present study aimed to compare the immunoexpression of DSPP, PITX2, CK14, CK19, Amelogenin, Vimentin, Calretinin, Syndecan-1, Glut-1, Galectin-3, KI-67, MCM7, Ciclin-D1, p53, Caveolin-1, B-RAFV600E, MOC-31, CD34, CD105, Bcl-2, Bax, Survivin, CD90, PTEN in tooth germ and primordial odontogenic tumor (POT) in order to elucidate its histogenesis and to obtain additional information about its behavior.
Methods: A total of 7 cases of dental germs and 7 specimens with previous diagnosis of POT were included. Twenty-four sections were made per sample for immunohistochemical technique and one for staining with Hematoxylin-Eosin. The project was approved by the Ethics Committee, UDELAR, Uruguay (file 17/17).
Results: Mesenchymal component of tooth germ was positive for Vimentin, Bax, Bcl-2, PITX2, Survivin, Ciclin-D1, MCM7, Ki-67 and p53. Amelogenin was positive in extracellular matrix. CD34 and CD105 were variably positive in blood vessels, whereas PTEN was negative in all the mesenchyme. Inner epithelium cells were positive for DSPP, CK14 and focally positive for CK19, Amelogenin, Vimentin, Glut-1, MOC-31, Caveolin-1. Expression was variable for Syndecan-1, p53, Bax, MCM7, Ciclin-D1, Ki-67 and PTEN. BRAFV600E, Galectin-3, CD90 and Calretinin were negative in all cases.

In POT, epithelial cells showed positivity for DSPP, CK14 and 19, whereas Amelogenin, Glut-1, MOC-31, Caveolin-1, Galectin-3, p53, Bax, Bcl2, Survivin and PTEN showed focal expression. Mesenchymal component was positive for Vimentin, PITX2, Syndecan-1, CD105, CD34, Ciclin-D1, Bax, Bcl2, Survivin and p53, whereas PTEN, DSPP and CD90 showed moderate positivity. Ki-67 and MCM7 were expressed in less than 5% of tumoral cells. BRAFV600E and Calretinin were negative in all cases.
Conclusions: Comparing tooth germ with POT allowed us to confirm its odontogenic origin and suggest its development from early stages of odontogenesis, considering it a benign tumor with low proliferation rate and moderately vascularized.