Case report: computed tomography demonstration of renal papillary necrosis.

Renal papillary necrosis has been diagnosed by intravenous urography and ultrasound, but no reports of the computed tomographic (CT) features have been published. We describe a case of renal papillary necrosis in a diabetic patient suspected on CT and confirmed by intravenous urography. CT demonstrated small kidneys, 'ring shadows' in the medullae, contrast filled clefts in the renal parenchyma and renal pelvic filling defects. In patients with poor renal function where intravenous urography may be difficult, CT may demonstrate necrotic papillae allowing the diagnosis of renal papillary necrosis to be made.