Robert L. Lebowitz, M.D. Children' s Hospital, Harvard Medical School Boston, Massachusetts

Prenatal diagnosis of right renal tumor.  Ultrasound imaging at 5 days of age confirmed the finding of replacement of the upper pole of the right kidney by a mass  (Figure 1) .  The "swirled" appearance on ulrasonography is typical for mesoblastic nephroma and has been likened to the appearance of a uterine fibroid.  The finding or replacement of the upper pole of the kidney by the mass was confirmed on MRI (Figure 2).  He underwent a right nephrectomy.