Abstract

The purpose of this study is to discuss the ultrasound and computed tomography findings of diffuse xanthogranulomatous pyelonephritis.

Abdominal ultrasound (US) and computed tomography (CT) examinations were performed on eight patients (3 male and 5 female), aged between 17 and 67, who had flank pain, fever, weight loss and malaise.

Diffuse involvement pattern of xanthogranulomatous pyelonephritis was found in three right, six left kidneys. In one case there was bilateral xanthogranulomatous pyelonephritis. The common US and CT findings were enlargement of the kidney, enlargement of the adjacent fatty planes and stone formation (five of which were staghorn shaped, two located at the ureteropelvic junction and two in the calices). In eight kidneys hydronephrosis was present. In three cases perinephritic abscess and in one case abscess in the psoas muscle were detected. In the contrast enhanced computed tomography examinations seven kidneys had no contrast excretion while two kidneys were seen to have delayed functions.

Xanthogranulomatous pyelonephritis is a rare chronic inflammatory disease of the kidney characterized by destruction of the renal parenchyma and the adjacent fatty planes by granulomatous tissue, which contains lipid-laden macrophages. Radiologic differential diagnosis from malignancy is difficult in the focal form. Whereas in the diffuse form, detection of a non-functioning large hydronephrotic kidney with stone formation, in addition to parenchymal and adjacent fatty plane changes are the radiological findings enabling the diagnosis.