Immunohistochemical studies of ameloblastoma with special emphasis on keratin.

: Ten cases of ameloblastoma including a case of gingival origin and a case of atypical ameloblastoma were studied immunohistochemically, especially with monoclonal and polyclonal anti-keratin antibodies. Stellate reticulum cells reacted strongly with monoclonal and polyclonal anti-keratin antibodies but columnar cells were reacted weakly. The level of keratinization of columnar cells was similar to that of the basal cell layer of the gingival squamous epithelium. Our immunohistochemical studies suggested that the process of keratinization-ameloblastoma follows the sequence of 1) cuboidal cells 2) columnar cells 3) stellate reticulum cells and 4) metaplastic squamous cells. The findings also disclosed the epithelial nature of granular cells. The reactivity of the components of atypical ameloblastoma differed from that of other cases. Other positive "markers" in ameloblastomas included CEA and CA19-9, but no particular histologic differences were observed between positive and negative cases.