Expression of proliferation-associated proteins (proliferating cell nuclear antigen and Ki-67 antigen) in Bowen's...

Bowen's disease and invasive squamous cell carcinoma arising in Bowen's disease (Bowen's carcinoma) were investigated immunohistochemically with regard to their expression of proliferating cell nuclear antigen (PCNA) and the Ki-67 antigen. Both proliferation-associated proteins were found in all layers of the tumours, and were present in nuclei of any size and shape. The nucleoli lacked PCNA immunoreactivity, but they expressed the Ki-67 antigen. The PCNA labelling index was 36.9 +/- 12.6% in Bowen's disease (n = 16), and 40.7 +/- 11.0% in Bowen's carcinoma (n = 3). The Ki-67 antigen labelling index was 43.6 +/- 16.7% in Bowen's disease (n = 16), and 51.7 +/- 11.6% in Bowen's carcinoma (n = 3). Dyskeratotic cells were positive for PCNA and the Ki-67 antigen, suggesting that these cells are not in a post-mitotic state. We conclude that in dyskeratotic cells of Bowen's disease the cell cycle is interrupted by nuclear disorganization.