Solution: Lymphoma involving the kidneys is actually relatively common with up to 1/2 of autopsies in patients who die of lymphoma showing renal involvement. However, it is less frequently identified on imaging and it is rare to have primary lymphoma of the kidneys. When it occurs, it generally has one of two manifestations. The most common manifestation is like this case where there are multiple rounded, hypoattenuating/hypoenhancing masses (unilateral or bilateral), or it can be a more diffuse, infiltrative process with the main finding being poor corticomedullary distinction and renal enlargement. A mantle/rim of soft tissue surrounding the kidneys has also been described. These patients may require biopsy to differentiate renal lymphoma from multiple renal cell carcinomas, metastases, or transitional cell carcinoma if there are not other more typical sites of disease. Treatment is with chemotherapy +/- radiation.