False-positive lesions detected by fluorescence cystoscopy: any association with p53 and p16 expression?

To determine p53 and p16 status as molecular markers of bladder cancer, in histologically proven benign bladder biopsies, obtained from lesions suspect for malignancy as judged by fluorescence cystoscopy. Immunohistochemical (IHC) staining was performed for p53 and p16, using the antibodies DO-7 and AB-4, respectively. The tissue sections were scored in percentages of nuclear staining for p53 and p16. Of 247 biopsies, 41/49 lesions appeared suspicious on fluorescence cystoscopy, but were histopathologically benign. 2/40 (5%) were > or =20% p53 positive as compared to 7/128 (5.5%) of all histopathologically benign biopsies. 24/37 (64.9%) were p16 negative (<5% positive cells) as compared to 84/125 (67.2%) of all benign biopsies. Most biopsies had a moderate to high degree of chronic cystitis. False positive lesions of fluorescence cystoscopy did not differ from benign lesions detected by standard white light cystoscopy with regard to p53 and p16 immunoreactivity. Little evidence remains for these lesions to be pre-malignant.