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

12-year-old girl presented with a severe febril illness, infected urine, and severe left-sided flank and abdominal pain.   A plain film of the abdomen showed a large stone (arrow) in the region of the left kidney.   There was splinting of the spine convx to the right, in order to protect her left side.   The stone, presumably in the collecting system of the left kidney, was located more lateral than expected.(Figure 1).   An IVP showed a hypertrophied right kidney and no funciton of the left kidney.(Figure 1).   A non-enhanced CT scan,(Figure 2).  except for contrast material from the IVP, showed a normal right kidney and on the left, there was nonfunction of the kidney, many stones, and a large psoas abscess. nbsp; There was gas in the kidney and in the retroperitoneum. nbsp; The kidney was removed, and she was found to have a large psoas abscess and a left kidney with no normal renal parenchyma, filled with pus and stones. nbsp; She had no diabetes or underlying problems and no sign of xanthogranulomatous material at pathology. (Figure 3)