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Xanthogranulomatous Pyelonephritis

Created: 9/1/2006


Xanthogranulomatous Pyelonephritis (XGP)


Definition: Chronic inflammatory disorder of the kidney characterised by a mass originating in the renal parenchyma



  • Schlagenhaufer first described XGP in 1916
  • Characterised by a spreading, diffuse inflammatory reaction forming a suppurative/gangrenous lesion with multiple pockets of pus
  • Shares many characteristics with a true neoplasm in terms of its radiographic appearance and ability to involve adjacent structures or organs
  • Common association with Proteus or E-coli infection (Pseudomonas also implicated)
  • Kidney is usually non-functional



  • Occurs in approximately 1% of all renal infections
  • Rare in the paediatric population
  • 4 times more common in women than men
  • Fifth and sixth decades of life


Aetological Risk Factors

  • long-term renal obstruction and infection
  • Stones- 75% of patients (often staghorn)
  • Diabetes or immunocompromised patients
  • Abnormal lipid metabolism has been hypothesised



  • Pathognomonic microscopic feature is the lipid-laden "foamy" macrophage
  • Accompanied by both chronic- and acute-phase inflammatory cells



  • Neoplasm like properties capable of local tissue invasion and destruction
  • Mass of yellow tissue with regional necrosis and haemorrhage
  • Focal abscesses

Signs and symptoms

  • Chronically unwell
  • Anorexia, fevers, weight loss
  • Flank/loin pain usually dull and persistent
  • Urine typically has both leukocytes and bacteria present
  • Erythrocyte sedimentation rate is frequently elevated
  • XGP is notorious for fistulisation-pyelocutaneous and ureterocutaneous fistulae are well described
  • NB. Renal cell carcinoma may be indistinguishable from XGP radiographically and clinically
  • NB. Diagnosis of XGP must be made histologically



Calcification may be seen on the plain film

Non-functioning kidney on affected side



Heterogenous nonenhancing mass in a hydronephrotic nonfunctioning kidney

Mass may appear to involve adjacent organs

Staghorn calculus is often found within the collecting system



Surgical removal

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