Aim: The aim of this paper was to evaluate the pathologic concordance of bilateral renal masses and the influence of synchronous or asynchronous occurrence on patient long term survival.
Methods: Thirty-one consecutive patients with bilateral synchronous (N.=17, 55.0%) or asynchronous (N.=14, 45.0%) renal masses were retrospectively reviewed from January 2000 to December 2010. We included all patients with confirmed diagnosis on pathologic examination of a specimen or a percutaneous biopsy and evidence of angiomyolipoma on CT. Survival was assessed using the Kaplan-Meier method. RESULTS. The first lesion was larger than the second (60 vs. 30 mm, P<0.001). Pathologic concordance rate between tumors was 87.1%. A clear cell carcinoma was associated with a papillary carcinoma in 3.2%, and an angiomyolipoma in 6.4%. Median time of occurrence of a metachronous lesion was 50 months (IQR: 24; 92). Disease-free survival at 5 and 10 years was 87.2% and 78.5%. No statistical difference in disease free survival was observed between synchronous and metachronous tumors. conclusion: Discordant pathology between bilateral renal masses is uncommon, with a slight probability of benign tumor. Occurrence of a metachronous tumor can exceed 10 years.