Xanthogranulomatous pyelonephritis: a critical analysis of 26 cases and of the literature.

Manifestations of xanthogranulomatous pyelonephritis in 26 patients closely mimicked those of neoplastic and other inflammatory renal parenchymal diseases. Middle-aged or older women were affected most often. Most patients presented with anemia, chronic febrile illness, a painful tender flank mass and recurrent urosepsis. Some features of nephrogenic hepatic dysfunction were present in 13 patients. Bacterial cultures of renal tissue were almost always positive but the spectrum differed considerably from that of the bladder urine. Urographically, a renal mass lesion was encountered in 62% of the patients, nephrolithiasis in 38% and a functionless kidney in 27%. Angiographically, none of the 4 mass lesions studied was distinguished from hypernephroma. Indeed, a correct preoperative diagnosis was made in only 1 instance. There were 3 stages of xanthogranulomatous pyelonephritis recognized. Treatment consisted of nephrectomy for diffuse or advanced stage disease or both (21 patients), excision of the diseased renal segment for localized and low stage disease (2 patients) and renal biopsy (3 patients). Xanthogranulomatous pyelonephritis did not recur but in some patients bacteriuria continued or hypertension developed.