The routine use of computed tomography (CT) for the staging and follow
-up of malignant neoplasm has improved the detection of secondary spre
ad to the kidneys. This essay illustrates the gamut of the CT aspects
of such secondary lesions. Seven main patterns of metastatic features
are identified. Some of these patterns appear to reproduce the same ra
diological features seen in the corresponding primary lesions. Where f
easible, differential diagnostic criteria are offered.