Xanthogranulomatous Pyelonephritis: Angiographic Considerations

THE ANGIOGRAPHIC pattern elicited by focal parenchymal and vascular injury is distinctive in most cases of pyelonephritis. Xanthogranulomatous pyelonephritis is an unusual form of chronic pyelonephritis, often presenting as a dominantly proliferative mass, with few symptoms typical of acute or chronic infection. It may be confused, both clinically and radiographically, with other benign nephropathies as well as with carcinoma of the kidney (1, 2). The histologic appearance is characterized by replacement of renal parenchyma by lipidladen macrophages within areas of granulomatous reaction. Rios-Dalenz and Peacock (3) in 1966 recorded 67 cases in a search of the literature and described 4 of their own. In the same year Becker (4) included an angiographic description, reportedly the first, in his case presentation. An awareness of the condition is essential, particularly with the availability of selective angiography in evaluating renal lesions. This report includes two cases of xanthogranulomatous pyelonephritis with dissimilar renal enlargement. One presented as a pyonephrosis and the other as a solid mass and perirenal abscess. CASE I: A 46-year-old Negro sought hospital admission because of right back pain and an abdominal mass, both of which had developed over the preceding two weeks. He was paraplegic following a back injury ten years earlier. Physical examination revealed a 5 × 7-cm, tender, fluctuant, right abdominal mass. Pain sensitivity below each groin was absent; the lower extremities were immobile and wasted; urinary incontinence was present. The temperature was 100° F (37.8° C), blood pressure, 120/70, and pulse, 80. The white blood count was 13,500. Urinalysis showed protein (3+) and innumerable red blood cells, white blood cells, and bacteria. Significant numbers of E. coli, P. mirabilis, and Aerobacter species were cultured from the urine. Blood urea nitrogen was 20 mg per 100 mI. Intravenous urography several hours following admission showed a normal left kidney and nonfunction on the right side. On the day of admission a large right renal abscess associated with pyonephrosis was incised and drained. Biopsies of the kidney and an adjacent lymph node were obtained. The abscess contained 1,500 ml of purulent material from which a pure growth of E. coli was cultured. Microscopic sections of the renal biopsy showed chronically inflamed, well vascularized fibrocollagenous tissue containing abundant xanthoma cells. The lymph node was similarly involved. The pathologic diagnosis was xanthogranulomatous pyelonephritis. Five days following surgery, selective renal arteriography was performed for further evaluation of the involved kidney (Fig. 1). The patient's subsequent course was uneventful, and he was discharged from the hospital improved.