Xanthogranulomatous pyelonephritis in adults: clinical and radiological findings in diffuse and focal forms

To describe the clinical and radiological features of focal and diffuse xanthogranulomatous pyelonephritis (XGP) in adults.

A retrospective review of the clinical data, laboratory findings, imaging features, and surgical treatment of 13 cases of histologically proven XGP diagnosed between January 1993 and December 2005 was undertaken. There were 10 women and three men with a mean age of 55.2 years (range 30-87 years). All patients underwent both sonography and computed tomography (CT) of the kidneys. Magnetic resonance imaging (MRI) was performed in two patients.

XGP was diffuse in 11 patients and focal in two patients. Fever, anorexia and weight loss, urinary symptoms, and flank pain were the most common manifestations. Urinary tract infection was found in eight patients. Sonography and CT showed diffuse kidney enlargement in seven cases and atrophy in five cases; a solitary solid mass was found in two patients. Hydronephrosis was noted in nine cases, staghorn calculus in six, and extensive pararenal disease in six. MRI failed to provide the preoperative diagnosis in the two patients with focal XGP. Total or partial nephrectomy was performed without postoperative complications.

Although rare, XGP is the main differential diagnosis of malignant renal neoplasia. The definitive diagnosis depends on histological examination of the operative specimen. Preoperatively, the diagnosis can often be suspected based on imaging studies, primarily CT.