Renal metastases: The spectrum of CT and sonographic appearances

The increasing awareness of renal metastases is due to the routine use of CT and the longer survival of patients. The authors observed 26 patients with renal metastases arising from a variety of primary tumors, including colon carcinoma (n = 6), lung (n = 6), breast (n = 3), head and neck (n = 2), melanoma (n = 4), testicular (n = 1), soft-tissue sarcoma (n = 2), and an unknown primary (n = 2). CT was performed in all patients and biopsies were obtained in 18. Their findings can be summarized as follows: Colonic metastases were large and solitary, mimicking secondary primary tumors. Melanoma had a prediliction for the perinephric space and contiguous involvement of the kidney. The other malignancies produced small, ill-defined multiple renal masses that usually did not cause contour deformities of the surface of the kidney. Renal metastases were a late manifestation of malignant disease; however, three patients survived more than 2 years after renal metastases were discovered. In the presence of widespread metastatic disease and a typical CT or US appearance, biopsy of a new renal mass is not warranted