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

This 14-year-old boy was noted to have scoliosis on physical examination. An x-ray of the spine showed a congenital thoracic vertebral anomaly. A CT scan confirmed the anomaly. An MRI scan was done to asses the cord and to look for associated renal anomalies. The most commone renal anomaly is a solitary kidney. The MRI scan was read as an abnormal right kidney measuring 9.0 cm in length (figure 1). THis was "confirmed" on an ultrasound exam with the right kidney measuring 4.2 cm (figure 2). The left kidney was noted to be hypertrophied but otherwise normal. He was referred here, where a DMSA scan showed no uptake by the right kidney. He underwent laparoscopy for nephrectomy of what was thought to be an abnormal nonfunctioning right kidney. The right kidney was not found. It was then discovered that he had no right vas and no right hemitrigone. Review of the images showed that the right colon and the duodenum occupied the empty right renal fossa and mimicked an abnormal kidney (figure 3).