An investigation into the origin and nature of 'amyloid' in a calcifying epithelial odontogenic tumour.

Fresh and fixed tissue from a resection specimen of a calcifying epithelial odontogenic tumour (CEOT) was prepared for histological, histochemical, immunological and biochemical investigation in order to study the nature of the amyloid-like material. The fixed tissue gave positive reactions with Congo-red, Thioflavin T and the dimethylamino benzene (DMAB)-method for tryptophan. The diazotization-coupling (DC) method for tyrosine was negative. The major protein purified from the unfixed tissue by sequential gel filtration had a molecular weight of 9,800. The amino acid analysis of this protein had similarities with tuft enamel protein, immune amyloid and the variable light chain component (VK). From the data obtained in this study, it is not possible to determine the precise nature of the amyloid-like material in this CEOT. However, the results do support the concept that 'amyloid' should be considered as a term describing a broad group of related proteins.