Multifocality in renal cell carcinoma: A bilateral event?

Objectives: The major disadvantage of nephron-sparing surgery for renal cell carcinoma is the risk of local recurrence. This is most likely a manifestation of undetected small additional tumors in the renal remnant. To define more clearly the incidence and nature of unilateral and bilateral multifocal tumors, an autopsy study was undertaken.

Materials and methods: In a series of 14,793 autopsies from 1985 to 1995, 260 renal cell carcinomas were found. In all cases of renal cell carcinoma a search for small renal lesions was performed in the apparently normal-appearing portion of the kidneys. Every kidney was serially and systematically cut (5 mm) to probe for intraparenchymal lesions.

Results: Of the 260 renal cell carcinomas 36 cases (13.85%) had multifocal malignant and/or benign nodules. The number of the additional nodules ranged from 2 to 18. 12% of the malignant multifocal carcinomas were limited to the ipsilateral kidney and 88% were bilateral. The average size of the multifocal renal lesions was 8.7 x 9.0 x 9.5 (range 3-23) mm. Renal cell carcinomas with low stage and good grading have a higher incidence of multifocal nodules. No significant difference was found with regard to metastasized and nonmetastasized renal cell carcinomas. In 38.1% of all chromophilic renal cell carcinomas additional nodules were found.

Conclusions: Multifocality in renal cell carcinomas cannot be predicted reliably, although the papillary histological pattern, good grading and low staging seems to be associated with a higher incidence of multifocality. Nearly 90% of the multifocal nodules were bilateral.