[Spontaneous renal rupture due to xanthogranulomatous pyelonephritis; a case report].

A 47-year-old female was admitted with colicky pain in the left flank. Ultrasonography and abdominal CT revealed left perirenal hematoma. Abdominal CT revealed a multilocular cystic lesion in the upper pole of the left kidney. Renal angiography revealed left renal cell carcinoma. Left nephrectomy was performed under a tentative diagnosis of left renal cell carcinoma. However, pathological diagnosis was xanthogranulomatous pyelonephritis. Xanthogranulomatous pyelonephritis is an atypical form of chronic renal parenchymal infection that can be classified as diffuse type or focal type. Preoperative diagnosis of focal xanthogranulomatous pyelonephritis is difficult because of clinical and radiological similarities to renal cell carcinoma. Our case is presented with a brief review of the literature.