The authors present their experience involving seven patients with histopathologic diagnosis of xanthogranulomatous pyelonephritis who were submitted to preoperative computed tomography (CT).

The results are the following:

a) stones (86 percent of the cases), b) increase in renal volume, c) hydronephrosis, d) density measurements (from 14 to 29 HU), e) enhancement found in al cases, f) extrarenal involvement (all cases). CT fas shown to be a reliable method in characterizing xanthogranulomatous xyelonephritis and extrarenal involvement.