Figure 4a. Surgical calcification in a 67-year-old asymptomatic man. (a) Axial unenhanced CT scan shows an irregular nodular calcification (large arrow) in a cystic mass of the left kidney. In addition, there is septal calcification (small arrow) and nephrolithiasis. (b) Contrast-enhanced CT scan shows focal nodular enhancement (arrow) adjacent to the irregular calcification.