Significance of the nonneoplastic renal parenchymal findings in robotic partial nephrectomy series

Aim: To describe the pathological characteristics of the peritumoral non-neoplastic renal parenchyma (NNRP) and to investigate their impact on long-term renal function after partial nephrectomy. Materials and methods: In our institutional robotic partial nephrectomy database, we identified 394 cases with pathological assessment of the NNRP and long-term postoperative renal functional follow-up. The NNRP was classified as normal (healthy renal parenchyma) or abnormal, based on the presence of arteriosclerosis, glomerulosclerosis, interstitial fibrosis, interstitial inflammation, and/or tubulopapillary hyperplasia. The primary outcome was a ≥ 20% decline in estimated glomerular filtration rate (eGFR) at 6 and 12 months after surgery. Multivariable analysis was used to assess the association between NNRP and eGFR decline, with adjustment for demographic, clinical, and tumor factors. Results: Overall, 250 (63.5%) pathological specimens had abnormal NNRP features. The most prevalent isolated benign pathological feature was glomerulosclerosis (18.0%), followed by arteriosclerosis (16.8%), interstitial inflammation (12.4%), interstitial fibrosis (1.2%), and tubulopapillary hyperplasia (0.4%). The abnormal NNRP group was associated with older age (p =.01), preoperative diabetes mellitus (p =.01), and preoperative hypertension (p =.01). The preoperative eGFR was significantly lower in the abnormal NNRP group (p =.01). NNRP abnormalities were not significantly associated with eGFR decline at either 6 or 12 months. The only independent predictor of eGFR decline was warm ischemia time (p =.01), and this association was only observed at 12 months. Conclusion: NNRP features are associated with preoperative comorbidities and lower baseline eGFR; however, they are not independent predictors of long-term renal functional preservation after partial nephrectomy.