Robot-assisted partial nephrectomy (RAPN) is the guideline-recommended approach for localized renal masses when feasible, providing excellent oncological control and renal function preservation. During tumor excision, intraoperative pseudocapsule rupture may occur, particularly in certain histological subtypes, and could theoretically increase the risk of recurrence. However, its association with perioperative outcomes, surgical margins, and tumor histology remains unclear. This study aimed to evaluate the frequency of pseudocapsule rupture, its relationship with tumor histology, and its impact on surgical, pathological, and early oncological outcomes following RAPN.
We included 258 patients who underwent RAPN for localized renal masses at our institution between January 2022 and December 2024. Patients were stratified according to the presence or absence of tumor pseudocapsule rupture during surgery (rupture vs no rupture). For all 258 patients, CT images and pathological specimens were reviewed by experienced radiologists and pathologists to determine the tumor pseudocapsule and its thickness. Demographic, clinical, and pathological variables were collected to compare the two groups using Wilcoxon rank-sum and Chi-squared or Fisher’s exact tests, as appropriate. Multivariable logistic regression model was used to identify independent predictors of tumor pseudocapsule rupture.
Among 258 patients, 45 (17%) experienced intraoperative tumor pseudocapsule rupture. No significant differences were found between groups in age, BMI, tumor size, cT stage, polar and anterior or posterior localization, or ischemia time, and, moreover, tumor pseudocapsule thickness on imaging and definitive pathology (p > 0.05). The median age was 60 years, and the median clinical tumor size was 3.2 cm. Most tumors were clear cell (38%) or papillary (25%) renal cell carcinomas. Tumor pseudocapsule rupture was more frequent among patients with papillary histology (45% vs 20%, p = 0.001). Positive surgical margins occurred in 4.7% of cases, without significant difference between groups (8.9% vs 3.8%, p=0.2). In multivariable logistic regression model, papillary histology was independently associated with an increased risk of pseudocapsule rupture (OR 7.88, p < 0.001), whereas other covariates, including tumor stage, pseudocapsule completeness, and warm ischemia time, were not significantly associated.
Intraoperative pseudocapsule rupture occurs more frequently in papillary tumors but does not significantly affect short-term surgical or oncological outcomes; longer follow-up is needed to assess its potential impact on recurrence.