Bilateral xanthogranulomatous pyelonephritis involving native kidneys in a renal transplant recipient: association with renal cell carcinoma and amyloidosis

Xanthogranulomatous pyelonephritis with associated renal cell carcinoma

Xanthogranulomatous pyelonephritis is associated with obstruction, stones and infection. CT is the mainstay of diagnosis, but appearances can mimic other conditions, including renal cell carcinoma. Nephrectomy is commonly recommended, but conservative treatment with antibiotics has been described after tissue diagnosis. We present a case of xanthogranulomatous pyelonephritis with concomitant renal cell carcinoma, which was an association that was suggested in 1988 and supported by subsequently reported cases. Conservative management of biopsy or cytology proven xanthogranulomatous pyelonephritis is unsafe, as an area of synchronous malignant tumour may be missed: we recommend it only in patients unfit for nephrectomy.

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.

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Nous présentons l’observation clinique d’un cas rare de pyélonéphrite xanthogranulomateuse (PXG) bilatérale chez un jeune patient âgé de 17 ans. La découverte progressive de l’infection a débuté par l’apparition de lombalgies bilatérales évoluant depuis un mois, sans autre signe associé. L’urotomodensitométrie penchait en faveur de deux masses rénales bilatérales, soit une masse polaire inférieure droite et une masse polaire supérieure gauche, toutes deux de densité tissulaire. Une biopsie écho guidée a suggéré la présence d’une réaction inflammatoire non spécifique. Une néphrectomie partielle polaire inférieure droite a été effectuée devant la forte présomption de tumeurs rénales malignes. Finalement, l’histologie a orienté le diagnostic vers une PXG. Il s’agit, à notre connaissance, du sixième cas de PXG focale bilatérale rapporté dans la littérature. Notre patient a reçu un traitement antibiotique à base de fluoroquinolone pendant un mois. L’évolution clinique s’est avérée bonne, et les lésions visibles à la tomodensitométrie se sont entièrement résorbées au bout d’un mois. Le patient vit toujours après un an et présente une fonction rénale normale.

Bilateral xanthogranulomatous pyelonephritis

Xanthogranulomatous pyelonephritis is an uncommon form of chronic bacterial pyelonephritis characterized by the destruction of renal parenchyma and the presence of granulomas, abscesses, and collections of lipid-laden macrophages (foam cells) replacing the renal parenchyma. This case report illustrates the clinical course of bilateral diffuse xanthogranulomatous pyelonephritis with a subtle manifestation in contrast to those typically presenting with fever, flank pain or urinary tract infection. The patient therefore received supportive treatment for 18 months without hemodialysis, instead of the curative treatment, bilateral nephrectomy, which would have caused immediate loss of residual renal function and dependence on hemodialysis.

A middle-aged woman with back and flank pain

Xanthogranulomatous pyelonephritis is an uncommon variant of chronic pyelonephritis that predominantly affects middle-aged women. Patients usually present with fever, back or flank pain, flank mass, and the constitutional symptoms of fatigue, malaise, weight loss, and anorexia. Rarely, they may present with a draining sinus. There is usually a history of urinary tract infection, obstruction, or instrumentation. Other abnormalities include anemia, leukocytosis, abnormal liver enzymes, pyuria, and hematuria. Mild azotemia may be present, but frank renal failure is rare. Urine and renal tissue cultures are frequently positive. The most commonly isolated bacterial pathogens are P. mirabilis and E. coli, but other organisms have also been implicated. A CT scan is the best radiologic imaging technique to discover the extent of inflammation as well as any involvement of adjacent structures. Lipid-laden macrophages called xanthoma cells characterize the disease at the microscopic level. Nephrectomy is curative. Careful preoperative evaluation will guide surgical planning in choosing an approach that provides adequate exposure of the affected tissue and facilitates subsequent care of the patient.