Diffuse large B-cell lymphoma involving the kidney. The growth pattern of renal lymphomas is usually interstitial. This low power scan shows sheets of tumor cells infiltrating in between nephrons and completely replacing the renal parenchyma. The lymphoma cells were positive for CD19, CD20, CD79a, BCL6, and kappa light chains. They were negative for CD3, CD5, CD10, CD30, and BCL2.