Here are some examples of the most common kidney cancer, renal cell carcinoma.
The first picture shows a kidney with a mass in its substance, beneath its capsule. The second picture is the same kidney, cut in half to show the yellow, hemorrhagic cnacer.
The third picture, from a different case, shows a renal cell carcinoma in the midportion of the kidney. It is yellow and contains some area which have liquefied.
The third picture shows the typical histopathology of a renal cell carcinoma. The cells have a clear cytoplasm and you can see their borders easily. Some of the clear staining is due to lipid, which make the tumors look yellow grossly. Like most renal cell carcinomas, this tumor is rich in blood vessels.