To determine the pathologic concordance rates in patients with bilateral synchronous sporadic renal tumors (BSSRT) and to determine factors predictive of concordance.

A retrospective chart review from 1985 to 2008 was completed with search criteria of all patients diagnosed with bilateral renal tumors. We included patients who had image-documented BSSRT or via reported history. We excluded patients with bilateral metachronous renal tumors, cystic renal masses, familial renal cell carcinoma (RCC) syndromes, urothelial cell carcinomas, and other variant histology. Univariate and multivariate analysis were conducted to assess for factors predictive of concordance.

We identified 297 patients eligible for analysis. RCC concordance was exhibited in 222 of 249 (89%) of patients. Benign tumor concordance, specifically oncocytoma, was found in 41 of 59 (71%) of patients. Factors such as age, gender, and tumor size on imaging did not have an association with concordance rates for bilateral RCC or bilateral oncocytoma. On multivariate analysis, multifocal tumors were associated with benign concordance (OR = 6.9, 95% CI = 1.6-29.2, P = .009).

Malignant and benign concordance rates are high for patients with BSSRT. Given the high concordance of RCC, the data support a management approach consisting of bilateral nephron-sparing surgery whenever possible. However, given the high concordance rate of oncocytoma in this population as well, less aggressive management (renal mass biopsy and surveillance) of the contralateral kidney may be considered after histologic confirmation of one side.