Imaging description

A four-year-old boy presented with large palpable flank masses bilaterally. An ultrasound (not shown) revealed bilaterally enlarged kidneys with homogeneous low echogenicity, resembling renal cortex. A contrast-enhanced CT was performed which showed a thick rim of non-enhancing, homogeneous soft tissue, surrounding centrally enhancing renal parenchyma (Fig. 62.1). Bilateral homogeneous non-enhancing soft tissue surrounding the renal parenchyma is a typical finding in diffuse bilateral nephroblastomatosis. Another patient with a similar presentation is shown in Figure 62.2. In this case, axial contrast-enhanced CT images demonstrate multiple lenticular, uniform, non-enhancing lesions in the renal cortex (Fig. 62.2), consistent with the more common multifocal type of nephroblastomatosis. On CT, focal nephroblastomatosis appears as low attenuation, subcapsular, or intraparenchymal lesions with poor enhancement relative to that of adjacent normal renal parenchyma. On MRI, focal nephroblastomatosis demonstrates low to intermediate signal intensity foci on both T1- and T2-weighted sequences. Both types of nephroblastomatosis typically resemble the normal renal cortex with regard to their echogenicity on ultrasound, and density and signal intensity on unenhanced CT and MRI. After contrast media injection, however, the lesions typically show no or only minimal enhancement. Contrast administration is helpful in differentiating nephroblastomatosis from Wilms’ tumor. The latter is typically inhomogeneous and enhances after contrast media administration.