Renal metastases: clinicopathologic and radiologic correlation

The clinical and radiologic features of 27 patients with renal metastases arising from eight different types of nonlymphomatous primary malignancies are presented. Renal metastases were generally detected late in the course of the malignancy. In 23 patients there were no symptoms referable to the kidney. Urinalysis was normal in nine patients and showed microscopic hematuria in nine, gross hematuria in four, and proteinuria in four. Radiologically, metastases were usually multifocal; however, metastases arising from colon, lung, and breast carcinoma were sometimes large, solitary, and otherwise indistinguishable from primary renal cell carcinoma. Three of four melanoma metastases and three of seven lung metastases infiltrated the perinephric space. Computed tomography was the most sensitive modality, depicting renal metastases in all 24 cases in which it was employed, followed by ultrasound and intravenous urography. In patients with a history of malignancy, renal metastases outnumbered renal cell carcinomas by approximately 4:1. This study indicates that a new renal lesion in a patient with advanced, noncurable cancer is more likely metastatic than primary and that biopsy in this setting is unlikely to be of aid.