Ossifying renal tumor of infancy: findings at ultrasound, CT and MRI.

A 4-month-old boy presented with persistent gross hematuria. At ultrasonography, a 3.5-cm echogenic mass with posterior shadowing and tumor vascularity was detected within the right renal pelvis. Precontrast CT showed a slightly hyperattenuating mass in the renal pelvis. At MRI the mass was heterogeneously hypointense on T2-weighted images and isointense on T1-weighted images. Contrast-enhanced CT and MRI both revealed peripheral enhancement of the mass. A histological diagnosis of ossifying renal tumor of infancy was made after open pyelostomy and tumor enucleation. We suggest that ossifying renal tumor of infancy should be considered when a mass with posterior acoustic shadowing and tumor vascularity on US, hyperattenuation on precontrast CT and hypointensity on T2-weighted MRI is seen within the renal pelvis of an infant with hematuria.