Calcified Renal Masses

Of 2,709 renal masses seen in a 10-year period, 111 contained roentgenographically visible calcium. This was found in 1 to 2% of the simple cysts and in 10% of renal-cell carcinomas. Calcium located non peripherally (within the mass) indicated a malignant lesion in 87% of cases. In another 8%, the masses were indistinguishable from renal-cell carcinoma on vascular studies, and this type of calcification required surgery; only 5% were benign cysts while peripheral eggshell calcification without calcium in the mass was usually associated with benign simple cysts, the risk of malignancy was still about 20%.