Ossifying renal tumor of infancy (ORTI): a case report and review of the literature.

We present the case of a 6-month-old boy who was referred to us with the chief complaint of intermittent painless gross hematuria. Computed tomography (CT) scan of the abdomen showed a partially calcified soft-tissue mass that was located in the lower pole of the right kidney and extended into the collecting system. Consequently, a partial nephrectomy was performed. The resected specimen showed that the tumor was partially calcified and occupied the renal pelvis. The histological findings suggested a diagnosis of ossifying renal tumor of infancy (ORTI), only 16 cases of which have been reported in the literature. The pathogenesis of this condition has not been well established. ORTI should be considered in the differential diagnosis for infants with gross hematuria and a calcified mass in the pelvicalyceal system.