Selected immunohistochemical features of conventional renal cell carcinomas coexpressing P53 and MDM2

Renal clear cell carcinoma (CCRCC) is an aggressive tumor for which new prognostic factors are needed. It has been suggested that CCRCCs co-expressing P53 and MDM2 could represent a special subgroup; therefore the aim of this study was to explore their immunohistochemical features. The material studied consisted of 470 cases of CCRCC. Immunohistochemistry for MDM2, P53, Ki-67, VEGF-A, VEGF-C, VEGF-D, GLUT1, CA9, and CK 7 was performed on tissue microarrays and assessed semi-quantitatively. On average, 6.6% or 5.3% of cases were P53+/MDM2+, depending on the P53 antibody used. The mean percentage of Ki-67 positive cells was 0.6% and p53-positive MDM2-positive cases showed significantly higher expression of Ki-67. The other immunohistochemical parameters studied did not differ between p53-positive MDM2-positive cases and the rest of the subtypes studied. Expression of almost all immunohistochemical markers differed with respect to pT stage; only for CA9 was the difference not significant. Furthermore, almost all immunohistochemical markers studied differed with respect to differences in grade; only for GLUT1 was the difference not significant. Our results suggest that with the exception of Ki-67, there are no significant associations between analyzed markers and the double P53+/MDM2+ phenotype.