How are emphysematous and xanthogranulomatous pyelonephritis diagnosed in men?

Updated: Jan 02, 2020
  • Author: John L Brusch, MD, FACP; Chief Editor: Michael Stuart Bronze, MD  more...
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Emphysematous pyelonephritis is an infection caused by gas-forming organisms. It results in a necrotizing infection of the renal and perirenal tissue. This process occurs mostly in patients with diabetes. Glucosuria enhances organism fermentation and carbon dioxide production. Obstruction of the upper urinary tract by calculi or necrotic renal papillae is common in this condition. The mortality rate for this complication is reported to be 43%. E coli is the most common pathogen, followed by Klebsiella and Proteus.

Intraparenchymal gas can be seen on imaging studies. This is distinctly different from gas occurring in the collecting system per se, which is not infrequent in pyelonephritis and is associated with a much better prognosis. Of emphysematous pyelonephritis cases, 10% are bilateral. Prompt treatment with antibiotics and nephrectomy or surgical drainage is required.

Xanthogranulomatous pyelonephritis is a rare, but severe, renal infection that is clinically difficult to differentiate from renal tumors. It can progress to nonfunction and swelling of the involved kidney, and it is often associated with obstructing calculi. Proteus is the most common pathogen, followed by E coli. A granulomatous reaction with suppuration results in destruction and swelling of the renal parenchyma.

Although no distinguishing characteristics can be observed upon imaging, the diagnosis can be made by examining cytologic specimens; the lipid material collects in macrophages (xanthoma cells). Pus and debris may fill the collecting system, creating the condition known as pyonephrosis.

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