Pathological heterogeneity in sporadic synchronous renal tumors: Is the histological concordance predictable?

To evaluate the pathological concordance rate of multiple synchronous renal masses (MSRM) presumed to be sporadic and to analyze predictive factors of concordance.

We identified from our institutional database patients with sporadic MSRM treated at our center between January 2000 and December 2015. All tumors were reviewed by a dedicated uropathologist. Pathological concordance rate was analyzed regarding clinical characteristics and preoperative imaging.

We included 112 patients: 50 had unilateral synchronous renal masses and 62 bilateral synchronous renal masses. A total of 291 tumors were analyzed, with an average of 2.6 tumors per patient. Overall, the malignant concordance rate was 91.6%, the pathological concordance rate was 67.3% and the grade concordance rate was 62.5%. In univariate analysis, predictive factors of histological concordance were bilateral synchronous renal masses (odds ratio [OR] = 3.39; 95% CI: 1.06-10.8; P = 0.04), age<60 years (OR = 3.04; 95% CI: 1.2-7.7; P = 0.02) and ≥3 lesions (OR = 2.41; 95% CI: 1.03-5.68; P = 0.04). In multivariate analysis, age<60 remained significantly associated with histological concordance (OR = 3.84; 95% CI: 1.24-11.9; P = 0.02).

The histological concordance rate of MSRM is low. Age at diagnosis <60 years, bilateral lesions and ≥3 tumors are predictive factors of histological concordance, but the pathological diagnosis remains difficult to predict. This heterogeneity is important to take into account, particularly when choosing the treatment upon the renal biopsy results from a single lesion.