High Grade T1 Papillary Urothelial Bladder Cancer Shows Prominent Peritumoral Retraction Clefting.

Differentiation of noninvasive from invasive papillary urothelial carcinoma can be challenging due to inability of proper orientation and thermal damage of transurethrally obtained material. The aim of this study was to analyze the presence and extent of peritumoral retractions in pT1 compared to pTa papillary urothelial carcinoma. Since peritumoral retractions may result from altered expression profiles of extracellular matrix proteins, we additionally analyzed the expression of matrix metalloproteinase 2 (MMP-2) and interleukin 8 (IL-8) in these tumors. The study comprised 50 noninvasive (pTa) and 50 invasive (pT1) cases of transurethrally obtained primary papillary urothelial carcinomas. The invasive nature of nests showing peritumoral retractions was confirmed immunohistochemically using antibody against collagen IV. Staining for MMP-2 and IL-8 was evaluated semiquantitatively using immunohistochemical staining index, calculated by multiplying the percentage of positive cells and staining intensity. Peritumoral retractions were found in 32% of pT1 carcinomas but in none of the pTa carcinomas. All tumors showing peritumoral retraction were high grade tumors. There was no statistically significant correlation between the expression of MMP-2 or IL-8 and the presence of peritumoral retractions or stage of the tumor (pTa vs. pT1). A statistically significant but weak correlation was found between MMP-2 and IL-8 expression (χ2-test, p=0,015). There was no statistically significant correlation between the presence of peritumoral retractions or MMP-2 expression and tumor recurrence and progression. Our study shows that, in doubtful cases, when differentiating between pTa and pT1 stages of papillary urothelial carcinoma, the presence of peritumoral retractions could favor the diagnosis of invasive neoplasm.