Rhabdoid tumor of the kidney presenting as an abdominal mass in a newborn.

Rhabdoid tumor of the kidney is a highly malignant tumor seen in the neonatal population with a characteristic clinical course. There are no known radiologic features to differentiate rhabdoid tumor of the kidney from other renal tumors; however, this report presents a newborn infant with rhabdoid tumor of the kidney who had a normal prenatal ultrasound at ten days prior to birth, followed by an abnormal prenatal ultrasound one day prior to birth. Observation of such a rapid development of a tumor in the kidney in a fetus or an infant should raise the possibility of a highly malignant tumor such as a rhabdoid tumor.