Abstract
A 73-year-old Japanese woman suffered from an elevated lesion, clinically diagnosed as cornu cutaneum, on the face. Light microscopically, there were numerous epidermal cells which included eosinophilic amorphous substances; electron microscopically, they were aggregates of tonofibrils. Immunohistochemically, there were granules, positive for papilloma antigen by the ABC method, in the horny layer. Based on these findings, a diagnosis of viral wart was made. There were many giant cells with polymorphous nuclei and some dyskeratotic cells in the center of the lesion, suggesting a transformation into Bowen’s disease. Electron microscopically, however, viral particles were not detected. Carcinogenesis, virus, and sunlight were discussed.
