Histopathologic analysis of peritumoral pseudocapsule and surgical margin status after tumor enucleation for renal cell carcinoma.

Abstract BACKGROUND: The oncologic safety of blunt tumor enucleation (TE) of renal cell carcinoma (RCC) depends on the presence of a continuous pseudocapsule (PS) around the tumor and on the possibility of obtaining negative surgical margins (SMs). OBJECTIVE: To investigate the PS and SMs after TE to define the real need to take a rim of healthy parenchyma around the tumor to avoid the risk of positive SMs. The risk of PS invasion related to other clinical and pathologic variables was also evaluated. DESIGN, SETTING, AND PARTICIPANTS: Between September 2006 and December 2007, data were gathered prospectively from 187 consecutive patients who had kidney surgery. Overall, 90 consecutive patients who had TE for RCC were eligible for the study. All specimens were evaluated using an image analyzer by a dedicated uropathologist. INTERVENTION: TE was done by blunt dissection using the natural cleavage plane between the tumor and the normal parenchyma. MEASUREMENTS: PS, SM, and routinely available clinical and pathologic variables were recorded. RESULTS AND LIMITATIONS: In 60 RCC tumors (67%) the PS was intact and free from invasion (PS-) while in 30 (33%) there were signs of penetration within its layers, with or without invasion beyond it. Indeed, 26.6% had PS that had been penetrated on the parenchymal side and 6.6% had penetration on the perirenal fat tissue side. The odds of having PS penetration increased significantly with an increase in clinical tumor size. PS penetration was also significantly associated with pathologic tumor dimensions and grade. In all cases the SMs were negative after TE. The present patients, followed for >2 yr, will enable us to correlate the risk of local recurrence with PS status. CONCLUSIONS: The risk of PS penetration is associated with clinical and pathologic tumor dimensions and grade. If there is PS invasion into normal parenchyma, the presence of a thin layer of tissue allows for negative SM even if a TE is performed. Comment in Is simple enucleation a minimal partial nephrectomy responding to the EAU guidelines' recommendations? [Eur Urol. 2009]Is simple enucleation a minimal partial nephrectomy responding to the EAU guidelines' recommendations? Ficarra V, Galfano A, Cavalleri S. Eur Urol. 2009 Jun; 55(6):1315-8. Epub 2008 Sep 4.