Calcifying epithelial odontogenic tumor. A histochemical and ultrastructural study

The tissue representing calcifying epithelial odontogenic tumor was taken from the posterior mandible of a 45-year-old Caucasian man. The histologic components of the tumor were: 1. sheets of polyhedral epithelial cells, 2. homogeneous substance, and 3. dystrophic calcification. The homogeneous substance reacted metachromatically to methyl and crystal violet and fluoresced yellow following Thioflavin T. However, it stained equivocally for amyloid with Congo red, and exhibited weak birefringence with polarized microscope and yellow fluorescence. The homogeneous substance consisted of densely packed microfibrils, 50–150 A in diameter, deposited within, as well as between, the tumor cells. Since the ultrastructural characteristics of the fibrillar material were unlike amyloid associated with the reticuloendothelial cells, it is postulated that the epithelial tumor cells may be producing some other fibrillar protein such as keratin or enamel matrix.