The incidence of multicentricity in renal cell carcinoma.

We established the frequency of cancer multicentricity in kidneys removed for renal cell carcinoma by examining 100 intact, formalin preserved kidneys with a diameter of less than 80 mm. (1987 to 1989). The mean diameter of the predominant tumors was 51 mm. (range 15 to 80 mm). After the capsules were removed the kidneys were serially sectioned at 3 mm. intervals, and cortical and intraparenchymal nodules were removed for histological examination. A total of 3 kidneys had multiple tumors found previously on routine pathological examination. In addition, we discovered another 11 nodules in 10 other kidneys. Four nodules had histological features consistent with carcinoma. The size of the nodules ranged from 2 to 5 mm. The rest of the nodules consisted of 3 adenomas, 1 adrenal rest, 1 oncocytoma coexisting with an adenoma and 1 carcinoma permeating through the lymphatic vessels. The mean size of the predominant tumors in the kidneys bearing multiple nodules was 49 mm. Therefore, we observed a 13% incidence of small renal nodules and a 7% multicentricity of renal cell carcinoma in kidneys from patients who underwent nephrectomy.