Adenomatoid odontogenic tumour: immunohistochemical demonstration of transferrin, ferritin and alpha-one-antitrypsin

Three cases of adenomatoid odontogenic tumour (AOT) were examined by morpho logical and immunohistochemical methods, to define the nature of tumour cel ls acid to determine the correlation between the occurrence of extracellula r eosinophilic amorphous material and epithelial tumour cells. The epitheli al tumour cell components observed in this study were divided into three ce ll types (cell type I: small compact cells in a solid nodule and pseudoglan dular cells in a duct-like structure; cell type II: peripheral elongated ce lls and spindle-shaped cells in a cribriform pattern; acid cell type Ill, m etaplastic squamous cells). The mesenchymal components consisted of eosinop hilic amorphous material and calcified material. Immunohistochemically, the type I cells reacted positively with antibodies to transferrin, ferritin a nd alpha-one-antitrypsin (alpha (1)-AT), whereas the type II cells constant ly indicated intense expression only for transferrin and alpha (1)-AT. All types of epithelial tumour cells reacted negatively with lactoferrin, alpha -one-antichymotrypsin, S-100 protein, S-100 alpha subunit and S-100 beta su bunit. Moreover, the eosinophilic amorphous material and calcified material examined were positive for the antibody against alpha (1)-AT. These materi als expressed immunophenotypes similar to those of the epithelial tumour ce lls, except for metaplastic squamous cells. The present study showed that i ron-binding proteins and proteinase inhibitor might be related to the patho genesis of AOT Furthermore, we indicated that the formation of eosinophilic amorphous material was associated with type I and type II cells.