The Prevalence of Malignancy in Satellite Renal Lesions and its Surgical Implication During Nephron Sparing Surgery

Purpose: We examined the prevalence of malignancy in a synchronous ipsilateral renal lesion identified during partial nephrectomy and evaluated its clinical significance. Materials and Methods: We retrospectively reviewed the records of 112 patients (114 renal units) who underwent nephron sparing surgery for a clinically localized sporadic renal mass between May 1995 and September 2005. Results: In 37 patients (32%) an additional lesion was diagnosed and excised intraoperatively, while in 67% these lesions were known before the operation and believed to be simple cysts. During surgery the additional mass was suspicious in 8 cases and in the remainder the mass was described as simple cysts that were excised. The mean size of the primary mass was 3.1 cm (SD 1.4). In 29 (78%) cases the primary mass was malignant, in 23 (79%) of these the second mass was benign and in the remainder renal cell carcinoma was diagnosed. In 8 cases (22%) the primary mass was benign and in 2 (25%) the secondary mass was malignant. Overall 22% of all second masses were malignant, and all were low grade and low stage. We found that 7% of second ipsilateral masses could be expected to harbor malignancy. Conclusions: Based on our data it is questionable whether total nephrectomy is mandatory as an immediate response to an ipsilateral synchronous second renal mass. The present findings may represent an increased appreciation of ipsilateral multicentricity compared to historical data.