Analysis of 39 cases of xanthogranulomatous pyelonephritis with emphasis on CT findings.

OBJECTIVE: In this retrospective study a review of the clinical, laboratory and radiologic features of 39 cases of xanthogranulomatous pyelonephritis (XGP) is presented. CT characteristics of XGP are analyzed in detail and the relevant literature is reviewed in order to determine the most typical among them.

MATERIAL AND METHODS: Pathologic material from 39 patients suffering from XGP was reviewed in order to confirm the initial diagnosis. Data compiled from the previous history of the patients, clinical, laboratory, urographic and CT findings, preoperative diagnosis, operative findings and postoperative period were analyzed.

RESULTS: Diffuse and focal forms of XGP were recognized in 38 and 1 cases, respectively. Fever, pain in the flank or abdomen, chills and malaise were the commonest symptoms. A non-functioning kidney and/or staghorn calculus were the commonest urographic findings. When available (15 cases), CT revealed multiple fluid-filled cavities in the affected kidney and demonstrated the extension of the disease to the perinephric spaces in all cases. All patients had undergone nephrectomies, which were characterized as difficult in 60% of cases, whereas two patients developed postoperative complications requiring re-exploration.

CONCLUSIONS: Nephrectomy for XGP may be followed by severe complications and appropriate patient preparation and operation planning is of great importance. CT is considered the imaging technique of choice for diagnosing the disease preoperatively and a plethora of CT characteristics have been described to date. Low-density fluid-filled areas within the renal parenchyma and findings indicating perinephric extension should be considered the most typical CT features of XGP.