The central odontogenic fibroma and the hyperplastic dental follicle: study with Picrosirius red and polarizing microscopy.

The central odontogenic fibroma (COF) is an uncommon odontogenic tumor in which the microscopic appearance is similar to that of the hyperplastic dental follicle (HDF). Distinction between these lesions is based mainly on their clinical and radiologic features. The collagen of 5 cases of COF and 13 cases of HDF was studied histochemically by staining sections with Picrosirius red and examining them by polarizing microscopy. Polarization colors of the collagen fibers of the lesions were recorded according to their width. While no differences were seen between the polarization colors of thin fibers (<0.8 mm) in both lesions, the polarization colors of thick fibers (1.6-2 mm) of COF were significantly more green and greenish-yellow as compared with those of HDF. These findings suggest that the Picrosirius red polarization method can be used as a diagnostic tool to differentiate between COF and HDF..