Immunocytochemical expression of Ki-67/p16 in normal, atypical, and neoplastic cells in urine cytology using BD...

The objective of this study was to investigate the expression of Ki-67/p16 in urothelial cells in cytological material.

There were 142 urines including normal controls, anonymous rest urine, controls after treatment for urothelial carcinoma (UC) and newly diagnosed UC. Immunocytochemistry for ki-67/p16 dual staining kit was performed on all specimens.

Eight high-grade UC and six anonymous specimens showed dual positivity. None of the low-grade UC or the control specimens after treated UC showed dual staining. Fifteen of 84 (17.8%) symptomatic cases were negative for both markers, and 59/84 (70.2%) showed positivity for both but not dual staining. Twenty-seven of 84 cases were positive for either Ki-67 (n = 22) or p16 (n = 5). Normal controls and benign specimens were negative for p16.

Co-expression of p16/Ki-67 in the same cells was found in 16.6% of the cases. All were high grade, and co-expression seems to have limited practical impact as an additional marker in urine cytology. Any positivity for p16 alone strongly indicates malignancy. Negative p16 accompanied by a positive Ki-67 rate at 5% or more could be considered as an additional marker for further clinical follow-up. Both markers, co-expressed and separate, can give additional information in follow-up patients after treatment for UC.