Figure 10a. Renal lymphoma in a 75-year-old woman who presented with left renal colic. (a) Initial unenhanced helical CT scan shows an enlarged left kidney with subcapsular soft-tissue attenuation (arrows) and an ill-defined lesion posteriorly. No obstructing stone was seen. (b) Contrast-enhanced CT scan helps confirm the presence of both subcapsular and parenchymal masses (arrows). Results of biopsy helped confirm the diagnosis of non-Hodgkin lymphoma.