Infiltrative tumor interface with normal renal parenchyma in locally advanced renal cell carcinoma: Clinical relevance and pathological implications

OBJECTIVES Locally advanced renal cell carcinoma is considered clinically aggressive, despite heterogeneity in survival outcomes. We investigated the clinical relevance and pathological implications of infiltrative tumor interface with normal renal parenchyma on preoperative imaging in locally advanced renal cell carcinoma. METHODS A total of 77 patients with locally advanced renal cell carcinoma (≥pT3a Nany M0) who underwent radical or partial nephrectomy (2008-2018) were analyzed. Preoperative dynamic computed tomography images were reviewed to assess radiological infiltrative features. A radiological infiltrative feature was defined as an ill-defined tumor interface with normal renal parenchyma. The tumor interfaces were analyzed histologically and compared with radiological findings. RESULTS The median tumor size was 6.4 cm. Lymphadenopathy was observed in four patients (5.2%). Clear cell renal cell carcinoma was diagnosed in 66 patients (86%) and Fuhrman grade was 3-4 in 38 patients (49%). A total of 30 patients (39%) showed radiological infiltrative features, which were significantly associated with larger tumor size and higher clinical T stage. The specificity and sensitivity of radiological infiltrative features in predicting pathological renal parenchymal infiltration were 90 and 64%, respectively. During a median follow-up period of 3.8 years, 27 patients (35%) developed cancer recurrences, and six patients (7.8%) died of renal cell carcinoma. Multivariable analysis showed that the presence of radiological infiltrative features was an independent risk factor for cancer recurrence. Cancer recurrence and cancer-specific mortality were significantly stratified by the presence or absence of radiological infiltrative features (P < 0.001 and P = 0.02, respectively). CONCLUSIONS Locally advanced renal cell carcinoma can show radiological infiltrative features preoperatively, which are significantly associated with unfavorable prognosis. Radiological infiltrative features on preoperative imaging correspond with a high specificity to pathological renal parenchymal infiltration.