Xanthogranulomatous pyelonephritis: segmental or generalized disease.

Xanthogranul omatous pyelonephritis of the kidney usually occurs in association with urinary tract infection, obstruction and/or calculi. The diagnosis usually is made when a nephrectomy is performed for a non-functioning kidney and/or a mass indistinguishable from carcinoma on radiological as well as gross examination. Segmental excision of the kidney for focal xanthogranulomatous pyelonephritis has been used rarely in the past. Focal involvement of the kidney with xanthogranulomatous pyelonephritis was encountered in 4 instances at our institution. The diagnosis was made incidentally in 3 patients during segmental excision of the involved parenchyma and/or cyst wall. We believe that the xanthogranulomatous process probably starts as a localized involvement in some cases and, if excised during this stage, further destruction of renal parenchyma can be prevented successfully.