Amyloidosis secondary to xanthogranulomatous pyelonephritis: an unusual case

Xanthogranulomatous Pyelonephritis Associated with Systemic Amyloidosis

Xanthogranulomatous pyelonephritis is rarely associated with systemic amyloidosis. To the best of our knowledge, this association has been described in only nine cases, including the present report. Our first patient, a 76-year-old woman, presented with chronic renal failure and xanthogranulomatous pyelonephritis in the right kidney associated with amyloidosis in the same kidney and ipsilateral adrenal. She has been followed up for 44 months and continues to do well with stable renal function and mild proteinuria. Our second patient, a 54-year-old woman, had a 25-year history of recurrent Proteus mirabilis urinary tract infections. She developed anuric chronic renal failure, becoming dependent on dialysis, and xanthogranulomatous pyelonephritis in the left kidney associated with amyloidosis in the same kidney. She died at 8 days postsurgery. The combination of lesions has been described in childhood and in adults presenting with chronic renal failure or nephrotic syndrome. Clinical remission of amyloidosis develops in a majority of the patients after the removal of the renal lesion. From a pathologic point of view our cases underline the importance of careful histologic examination of removed kidneys, even in conditions characterized by extensive destruction of renal tissue. To prevent the association with amyloidosis we emphasize the importance of early diagnosis and treatment of xanthogranulomatous pyelonephritis.

Amiloidosis secundaria a pielonefritis xantogranulomatosa: presentación de un caso y revisión de la literatura

Xanthogranulomatous pyelonephritis (XGP) is a rare entity characterized by the formation of inflammatory renal masses rich in macrophages loaded with lipids. It is usually secondary to repeated urinary infections and urinary obstruction due to stones, which produce slow destruction of the renal parenchyma, requiring nephrectomy. It may sometimes be associated to secondary amyloidosis that leads to the appearance of a nephrotic syndrome. We have conducted a search in the Medline database between the years 1967 and 2003 and we only found 6 cases in adults and 3 cases in pediatric patients with amyloidosis secondary to xanthogranulomatous pyelonephritis. During this same period, there are more than 570 citations that include more than 1,000 patients with isolated XGP, so that we estimate that amyloidosis that complicates a XGP should be less than 1% of all the XGP cases. We present a case of XGP in a 51 year old female patient associated to amyloidosis that initiated with nephrotic syndrome, analyzing the clinical characteristics of the 9 previous cases. We compared their clinical characteristics with those of 51 patients with xanthogranulomatous pyelonephritis without amyloidosis of a large classical series in order to characterize this clinical picture better.