Clear cell sarcoma of the kidney: CT, sonographic, and pathologic correlation.

The sonographic and computed tomographic findings in 12 children aged 1-6 years with clear cell sarcoma of the kidney were reviewed retrospectively. Tumor size, calcification, and internal architecture were characterized and correlated with the gross pathologic findings. All tumors were unilateral and large (8.5-16 cm in diameter). Except for one, all masses were predominantly solid, and all contained some well-defined portions of low attenuation or hypoechogenicity that represented tumor necrosis. In addition, seven tumors contained uncomplicated fluid-filled cysts with diameters ranging from a few millimeters to 5 cm. Extension into the inferior vena cava was not noted. The radiologic features of clear cell sarcoma of the kidney are common to all malignant renal neoplasms. Some cases, however, may have features that simulate those of benign conditions, such as multilocular cystic nephroma or segmental cystic dysplasia. No pattern was discerned that would permit discrimination between clear cell sarcoma of the kidney and the most common renal neoplasm of childhood, Wilms tumor.