Xanthogranulomatous pyelonephritis-presentation as acute renal failure in a child with a solitary kidney

A 4-year-old girl, who had been in perfect health, presented with the acute onset of renal failure and abdominal mass. Investigations revealed a solitary left kidney which on histology had the typical features of xanthogranulomatous pyelonephritis. The child had no previous history suggestive of chronic renal disease and had no radiologic evidence of renal osteodystrophy. She had no improvement in renal function and has gone on to hemodialysis and transplantation. The unique mode of presentation and the unusual features of this case are discussed.