Xanthogranulomatous pyelonephritis: critical analysis of 30 patients.

INTRODUCTION AND 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%).

CONCLUSION: 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.