title: Xanthogranulomatous pyelonephritis: critical analysis of 30 patients.
abstract: OBJECTIVE
  Xanthogranulomatous pyelonephritis (XGP) is a chronic inflammatory condition of the kidneys. Nevertheless, disparities between the pre-operative and pathological diagnoses are frequently encountered. We reviewed all patients with XGP over a 17-year period to identify and characterize the pre-operative and pathological characteristics of the disease in our patients.
  
  
  METHODS
  A comprehensive review of all nephrectomy patients with a pre-operative diagnosis of pyelonephritis at National Taiwan University Hospital from 1991 to 2008 with the pathological diagnosis of XGP was conducted to demonstrate the clinical and radiological characteristics of XGP.
  
  
  RESULTS
  XGP was diagnosed in 30 (18.6%) of the 160 nephrectomies performed for pyelonephritis. Of the 30 patients with XGP, 25 were women (83.3%) and 20 (66.7%) were overweight (body mass index >23). Their mean age was 55.17 years. The average serum creatinine level was 1.68 mg/dL. The image findings included renal calculi (56.7%), staghorn stones (26.7%), and spread of the disease to the retroperitoneum and psoas muscle (33.3%). Escherichia coli (36.7%) was the most prevalent pathogen. The mortality of the two-stage surgical treatment was zero, and morbidity developed in only 1 patient (4.8%).
  
  
  CONCLUSIONS
  The key to accurate pre-operative diagnosis is to keep risk factors in mind such as age, sex, and renal calculi. Clinicians should maintain a high suspicion of XGP for early recognition and be aware of the care of chronic kidney disease. Finally, the association between XGP and central obesity warrants further research.
authors.affiliation: Department of Internal Medicine, National Taiwan University Hospital, Yun-Lin Branch, Yun-Lin, Taiwan.
authors.forename: Chin-Chi
authors.initials: CC
authors.lastname: Kuo
authors.forename: Ching-Fang
authors.initials: CF
authors.lastname: Wu
authors.forename: Chun-Chieh
authors.initials: CC
authors.lastname: Huang
authors.forename: Yuan-Ju
authors.initials: YJ
authors.lastname: Lee
authors.forename: Wei-Chou
authors.initials: WC
authors.lastname: Lin
authors.forename: Ching-Wei
authors.initials: CW
authors.lastname: Tsai
authors.forename: Vin-Cent
authors.initials: VC
authors.lastname: Wu
authors.forename: Yung-Ming
authors.initials: YM
authors.lastname: Chen
authors.forename: Ming-Shiou
authors.initials: MS
authors.lastname: Wu
authors.forename: Tzong-Shinn
authors.initials: TS
authors.lastname: Chu
authors.forename: Kwan-Dun
authors.initials: KD
authors.lastname: Wu
mesh_terms: D000328:Adult; D000368:Aged; D000369:Aged, 80 and over; D003937:Diagnosis, Differential; D003952:Diagnostic Imaging / Q000379:methods*; D005260:Female; D005500:Follow-Up Studies; D006801:Humans; D015994:Incidence; D008297:Male; D008875:Middle Aged; D009392:Nephrectomy / Q000379:methods*; D011705:Pyelonephritis, Xanthogranulomatous / Q000175:diagnosis* / Q000453:epidemiology / Q000601:surgery; D012189:Retrospective Studies; D012307:Risk Factors; D015996:Survival Rate / Q000639:trends; D013624:Taiwan / Q000453:epidemiology