Infiltrative Renal Masses: Clinical Significance and Fidelity of Documentation

Abstract Background The prevalence of infiltrative renal masses (IRMs) and fidelity of documentation of infiltrative features remain unclear. Objective To investigate the prevalence/significance of IRMs and assess whether infiltrative features were documented preoperatively. Design, setting, and participants A total of 522 patients with renal tumors managed with partial/radical nephrectomy (2012–2014) whose pathology demonstrated locally advanced and/or aggressive histology were analyzed. Preoperative computed tomography/magnetic resonance imaging was retrospectively/independently reviewed by two radiologists. IRMs were required to have a poorly defined interface with parenchyma and nonelliptical shape in one or more distinct/unequivocal areas. Infiltrative features were defined as extensive or focal. Intervention Partial/radical nephrectomy. Outcome measurements and statistical analysis Cancer-specific mortality (CSM) was estimated using cumulative-incidence analysis. Significant and independent predictors of CSM were evaluated using Cox proportional hazard analysis. Conclusions Twenty-five percent of locally advanced/histologically aggressive renal tumors exhibited infiltrative features, although many were not documented as IRMs. Among this high-risk surgical population, infiltrative features were independent predictors of CSM, irrespective of whether they were documented or not. Our data suggest that infiltrative features should be assessed and documented routinely during evaluation of renal masses. Patient summary Infiltrative renal masses may be more common than previously appreciated, although many were not documented as infiltrative during preoperative evaluation. Our data suggest that infiltrative features have a strong impact on prognosis and should be assessed and documented routinely during radiologic and clinical evaluation of renal masses.