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Radiological Features of renal papillary necrosis

A 70 year old diabetic has chronically deteriorating renal function. An intravenous urogram reveals ring shadows and filling defects within dilated calyces. The most likely diagnosis is

  • a) pelvi-ureteric obstruction
  • b) horse-shoe kidney
  • c) medullary sponge kidney
  • d) renal tuberculosis
  • e) renal papillary necrosis

The correct answer is ( E )


Clinically, renal papillary necrosis is a spectrum of disease, most common in patients with diabetes, analgesic nephropathy or sickle cell disease. Patients may have an acute fulminating illness with rapid progression or may have a chronic disease that is incidentally discovered on excretory urography. Some patients may chronically pass necrotic tissue in their urine , and some may never pass papillae.

Although the diagnosis may be made from the passage of necrotic papillae in the urine, most often it is made from the excretory urogram. The radiographs show various degrees of renal involvement with either medullary or papillary changes causing irregular sinuses or medullary cavities or classic ring shadows. Retained necrotic papillae may calcify, especially in association with infection. Furthermore, this necrotic tissue may form the nidus for chronic infection. Opportunistic fungal infections have been reported. Renal sonography may be useful to diagnose papillary necrosis.

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