Objective: Superficial tumors including Ta, Tis, and T1 make up 75% of urothelial carcinomas of the bladder. While the behavior of these superficial urothelial cancers is relatively benign, invasive tumors have a significant mortality rate. However, Ta and T1 tumors might display different biological behavior. There is therefore a great need for biomarkers that can accurately distinguish the behavior of urothelial carcinomas in addition to tumor grade and stage. Our aim was to determine the immunohistochemical expression profile of insulin like growth factor II mRNA binding Protein 3 (IMP3) and its correlation with tumor stage and grade in benign urothelium and bladder urothelial carcinomas.

Material and Method: The expression of IMP3 in 91 patients with benign urothelium (20 cases), low grade invasive (17 cases) / noninvasive (20 cases) urothelial carcinoma and high grade invasive (20 cases) / non-invasive (14 cases) urothelial carcinoma was evaluated by immunohistochemistry in this study.

Results: IMP3 was not expressed in benign urothelium, low-grade non-invasive urothelial carcinoma and high grade non-invasive urothelial carcinoma. Expression of IMP3 was found in 11.76% of low-grade invasive urothelial carcinomas and 55% of high grade invasive urothelial carcinomas. Statistical analysis including χ2 tests showed that IMP3 expression of invasive urothelial carcinomas was statistically significant (p<0.000).

Conclusion: The detection of IMP3 only in invasive carcinomas although some of them were low grade showed that the expression of IMP3 may be related to aggressive behavior of urothelial carcinomas.