[Unexpected renal cell carcinomas found during the operation in renal calculus: report of two cases].

Case 1: A 58-year-old man was seen with dull pain over the left flank. The X-ray examination revealed a renal stone in the left kidney. On operation, a globular hard mass was found in the lower portion of the posterior aspect of the kidney from which a biopsy specimen was obtained. A frozen section study showed renal cell carcinoma, and nephrectomy was performed. The patient is well four years after the operation without recurrence or metastasis. Case 2: A 50-year-old man consulted with microhematuria pointed out in a physical examination. At the operation for renal stone, we found the mass in the lower portion of the kidney. A frozen section study of the mass revealed renal cell carcinoma. We performed nephrectomy and lymphadenectomy on the renal pedicle. The patient is well three years after the operation. We reviewed the cases of renal cell carcinoma associated with renal calculi reported in Japan and discussed how the nephrectomy should be performed according to the frozen section study.