Calcifying epithelial odontogenic tumor of pindborg.An electron microscopic study

Abstract

A calcifying epithelial odontogenic tumor of Pindborg was examined with the electron microscope. The tumor cells demonstrated fine structural features commonly seen in epidermal cells, i.e., intercellular bridges with desmosomes, intracytoplasmic tonofilaments, and well-developed hemidesmosomes. A thin linear condensation was observed within die lamina lucida of hemidesmosomes which probably represents a normal component of these attachments. A copious extracellular matrix was seen which was composed largely of fine fibrils, approximately 50 Å in width, aggregated to form a structure resembling a basal lamina. The possibility that this fibrillar extracellular matrix represents amyloid was discussed. Calcospherites were present within the matrix, occasionally in association with fragmented tumor cell cytoplasm. They appeared to lack collagen and were composed primarily of electron dense needles resembling hydroxyapatite.