[Xanthogranulomatous pyelonephritis and renal carcinoma. Report of a clinical case and review of the literature].

Xanthogranulomatous pyelonephritis is a rare disease of the kidney; renal parenchyma is replaced by lesions radiologically simulating clear cell carcinoma. We present a case of a 62-year-old diabetic woman observed at our institution for the appearance of back pain and dysuria. A CT scan revealed a large lesion of left kidney with psoas muscle infiltration and the patient undrwent a nephrectomy. Histology surprisingly showed a xanthogranulomatous pyelonephritis. Though recent reports demonstrated the feasibility of conservative management of XGP with antibiotics, the use of pre-operative biopsy is still limited by the risk of seeding and the high false-negative results. How to distinguish xanthogranulomatous pyelonephritis from renal cancer?