CT Findings in Progressive Xanthogranulomatous Pyelonephritis

Abstract

Resulting from recurrent subacute or chronic urinary infections, a chronic pyelonephritis develops, which can be represented as several entities. Xanthogranulomatous (XGP) pyelonephritis is one of those entities which has characteristic radiographic features. The inflammatory process following the recurrent infections causes destructions to the parenchymal wall of the kidneys and over time it is replaced with a mass of reactive granulomatous tissue, containing lipid-laden macrophages, which surrounds the typical form of calculi – staghorn calculi. These are the pathognomonic radiological signs. CT is the modality of choice in diagnostic imaging for xanthogranulomatous pyelonephritis for two reasons – in the most of cases it demonstrates a highly specific tirade of findings that allow a confident diagnosis and offers accurate follow-up of the disease which is of great importance for the further surgical treatment. We present the CT findings of a clinical case throughout 6 years long follow up of chronic pyelonephritis which advanced to development of XGP and a complication with purulent collection in the left kidney, which resulted in left sided nephrectomy. This article describes the role of diagnostic imaging and correlates the radiologic findings to the underlying disease process. Additionally, we emphasize the diagnostic importance of CT in treatment, follow-up and preoperative planning.