Xanthogranulomatous pyelonephritis in children: diagnostic and therapeutic aspects.

BACKGROUND: Xanthogranulomatous pyelonephritis (XGP) is an uncommon chronic, inflammatory disease of the kidney. Etio-pathogenesis, diagnosis and management of pediatric XGP is still obscure due to the limited number of cases. Therefore, a retrospective clinical study was carried out to present an updated picture of the entire spectrum of pediatric XGP based on our 30 years' experience covering one of the largest non-collected series treated in a single medical center.
METHODS: Records of children who were treated for XGP in our unit from 1970 to 1999, inclusive, were reviewed retrospectively. Information recorded for each patient included age, sex, past medical history, clinical characteristics, diagnostic procedures,treatment methods, histopathologic findings and outcome.
RESULTS: 17 children with a mean age of 6.6 +/- 0.8 years, consisting of 15 males and 2 females, were treated for XGP. Eight patients had a urological disease history and 4 of them underwent surgery for urinary calculi and exstrophia vesica repair. The most common presenting symptoms were abdominal pain, fever,weight loss and anorexia. Palpable flank mass was the most common physical examination finding. Left and right kidneys were involved in 10 and 7 patients, respectively. Diagnostic procedures were intravenous pyelography, retrograde pyelography, ultrasound scan and computerized tomography (CT). Renal calculi and/or calcifications and non-functioning kidney were the most frequent findings in radiologic investigations. By combining all these investigations, the preoperative diagnoses were XGP (n = 2), renal and/or perirenal abscess (n = 5), psoas abscess(n = 2), non-functioning kidney due to recurrent pyelonephritis(n = 4), Wilms' tumor and/or renal clear-cell carcinoma (n = 4). XGP was correctly diagnosed in only two patients based on cr findings. Drainage of the renal or psoas abscess was performed in 8 patients as an initial procedure (surgical drainage in 6 and ultrasound-guided percutaneous drainage in 2 patients). Surgical procedures included nephrectomy (n= 13), partial nephrectomy (n=2), nephrectomy and diversion of reno-colic fistula(n= 1), and renal biopsy and nephrostomy (n= 1). Operative and postoperative complications were colonic perforation (n= 3) and wound infection (n = 3). Complications were noted only in patients who underwent nephrectomy without initial drainage procedures. Histopathologic examinations showed diffuse and focal XGP in 14 and 3 patients, respectively.
CONCLUSION: XGP should be included in the differential diagnosis of all children presenting with perirenal or psoas abscess, renal mass and/or non-functioning kidney associated with/or without urolithiasis. Clinical awareness and a high index of suspicion is required to achieve the correct preoperative diagnosis and appropriate management. CT seems to be the most valuable imaging method for the diagnosis. We strongly recommend percutaneous drainage of the abscess and adjunctive antibiotic therapy prior to nephrectomy to avoid complications. Complete nephrectomy is the proper treatment for the diffuse form whereas frozen section biopsies followed by partial nephrectomy are mandatory for the proper treatment of focal disease.