The nature of ghost cells in calcifying odontogenic cyst: an immunohistochemical study.

Two solid and two cystic forms of calcifying odontogenic cysts were stained immunohistochemically to study keratin, carcinoembryonic antigen, epithelial membrane antigen, and S-100 protein expression in ghost cells. The patterns of immunoreactivity were compared with those of dentigerous cysts, odontogenic keratocysts, ameloblastomas, calcifying epitheliomas of Malherbe, and control samples. Immunostaining patterns of calcifying odontogenic cysts were found to be similar to the odontogenic lesions and different from calcifying epithelioma. It is concluded that ghost cells are "keratinizing" odontogenic cells showing aberrant differentiation. These cells should not be regarded as metaplastic. The similarity of the immunostaining patterns of cystic and solid calcifying odontogenic cysts supports the view that these lesions are two morphologic variants of the same entity.