| Abstract|| |
We herewith report 10 patients with xanthogranulomatous pyelonephritis (XGP) who were treated in our department between the years 1988 and 2000. The patients' age ranged from 20 to 60 years (mean 45 years); there were seven males and three females giving a male-female ratio of 2.3:1. Sixty percent of the patients were over 50 years old. The lesion was unilateral in all cases and pyonephrosis was found in seven patients. Nine cases had associated renal stones (90%), which led to non-functioning kidney in all these cases. Two cases had associated fistulae (one uretero-colonic fistula and one reno-cutaneous fistula). One case of focal XGP was found to be associated with renal cell carcinoma while a second patient with diffuse obstructive type of XGP and renal stone had associated transitional cell carcinoma of the renal pelvis. In all patients, the urine culture was negative. Pus culture revealed Escherechia coli in four cases (40%), Salmonella Para B in one, and no organism could be grown in four other cases. One case did not have any pus. All patients were treated with nephrectomy.
Keywords: Xanthogranulomatous pyelonephritis, Renal stone, Fistula, Renal cell carcinoma.
|How to cite this article:|
Fallatah A, Tarakji M, Amuesi J. Xanthogranulomatous Pyelonephritis: A Retrospective Study of 10 Cases and Review of the Literature. Saudi J Kidney Dis Transpl 2001;12:520-4
|How to cite this URL:|
Fallatah A, Tarakji M, Amuesi J. Xanthogranulomatous Pyelonephritis: A Retrospective Study of 10 Cases and Review of the Literature. Saudi J Kidney Dis Transpl [serial online] 2001 [cited 2021 Aug 5];12:520-4. Available from: https://www.sjkdt.org/text.asp?2001/12/4/520/33545
| Introduction|| |
Xanthogranulomatous pyelonephritis (XGP) is a rare and aggressive form of chronic bacterial infection of the renal parenchyma characterized by accumulation of lipid-laden foamy macrophages and destruction of the renal parenchyma, often associated with calculi, urinary tract infection and obstruction. , This entity was first described by Schlagenhaufer in 1916.  The disease is most frequently encountered in middle-aged patients (5th to 7th decade) and is seen predominantly in women (female-to-male ratio 3:1). In most cases, XGP is unilateral and leads to nonfunctioning enlarged kidney, particularly when associated with stones. Escherechia coli (E. coli) and Proteus mirabilis are the most common offending microorganisms.  We analyzed retrospectively 10 patients with XGP by clinical symptoms and signs, bacterial culture, laboratory results, radiographic investigations and association with renal tumors. The literature was reviewed and certain unusual cases, such as renocolonic and reno-cutaneous fistulae were described.
| Patients and Methods|| |
A retrospective review of the charts of all pathologically proved cases of XGP seen in our hospital between the years 1988 and 2000 was performed. All cases were reviewed with respect to symptoms and signs, laboratory, radiological and microbiological findings.
| Results|| |
A total of 10 cases with XGP were identified during the study period. All cases were unilateral, with the left kidney involved in six and the right, in four cases. The age of the patients ranged from 20 to 60 years with a mean of 45 years. Seven patients were male and three were female. The female-to-male ratio was 1:2.3; male patients thus predominated. Six (60%) of the patients were above 50 years of age. Pyonephrosis was found in seven patients (70%); nine patients (90%) had associated renal stones and all nine showed non-functioning kidneys on intravenous urogram (IVU) and isotope scan. Only one patient had associated diabetic mellitus (10%).
The most frequent presenting complaints were pain, fever and dysuria. The clinical features at presentation are summarized in [Table - 1].
The duration of symptoms ranged from two weeks to 10 years. The urine culture of all patients was sterile but the culture of the intra-operatively obtained pus revealed E. coli in four, and Salmonella More Details Para B in one case. The pus in four cases was sterile and in one case there was no pus.
Two cases were associated with tumors. The first was a 55-year old female who presented with right flank pain and fever. The IVU revealed non-functioning right kidney with staghorn calculus. The surgical pathology of the nephrectomized kidney showed transitional cell carcinoma of the renal pelvis with extensive sqamous metaplasia and changes of XGP. The perinephric fat was invaded by the tumor. The second case was a 55-year old male patient who was investigated for hypertension. The ultrasound, IVU and computerized axial tomography (CAT) Scan showed a solid parenchymal mass in the lower pole of the left kidney. The kidney was well functioning and there were no stones. The pathological study of the nephrectomized kidney revealed extensive involvement of the kidney and the perinephric fat by XGP with a localized growth of renal cell carcinoma.
Two cases were associated with fistulous tracts, the first one being a 35-year old male patient who had undergone left nephrolithotomy three years prior to admission. The patient had a non-functioning kidney on the left side with a reno-colonic fistula extending from the kidney into the descending colon. This fistula was proved by both retrograde pyelography and barium enema [Figure - 1],[Figure - 2]. The second case with fistula was a 50-year old male patient who had previously undergone nephrolithotomy twice with drainage of associated perinephric abscess. This patient subsequently developed a reno-cutaneous fistula.
Associated renal stones were seen in nine cases (90%) all of whom revealed non-functioning kidney due to complete obstruction. Stone analysis was performed in all these cases and revealed calcium oxalate mixed with calcium phosphate or calcium carbonate.
Of the 10 study cases, only one showed functioning kidney on IVU and this patient had focal XGP with partial obstruction. Another case of focal XGP showed non-functioning kidney due to complete obstruction. The remaining eight cases showed diffuse type of XGP. All cases were treated by nephrectomy.
| Discussion|| |
Xanthogranulomatous pyelonephritis is a rare and aggressive form of chronic bacterial infection of the renal parenchyma characterized by accumulation of lipid-laden foamy macrophages and destruction of the renal parenchyma, often associated with calculi and urinary tract infection and obstruction. 
In our study, the disease occurred predominately in middle-age men, although women predominated in other studies. The disease was unilateral in all cases, although cases with bilateral XGP have been reported. 
Histologicaly, the affected tissue contains lymphocytes, plasma cells, neutrophils and large macrophages with foamy cytoplasm full of lipid material. At times, these cells resemble those seen in renal clear cell carcinoma, and it may at times be difficult to distinguish the two solely on the basis of frozen section. 
Malek and Elder classified XGP into three stages : Stage I where the lesion is confined to the renal parenchyma; Stage II involving the peri-renal space; and Stage III where the lesion extends into the peri-renal and pararenal spaces. Extension into the adjacent organs leads usually to the formation of a draining sinus.
Approximately 80% of patients with XGP will present with the classic triad of radiological findings namely: (a) unilateral renal enlargement, (b) mal- or more frequently, non-functioning kidney and (c) large calculus in the renal pelvis or an obstructing ureteric stone. The most frequent presenting symptoms are flank pain, dysuria and fever. The disease usually presents with diffuse involvement of the renal parenchyma. However, we saw two cases of segmental (focal) XGP surrounding one or more calyces. In these cases, there is generally associated nephrolithiasis and peripelvic fibrosis, the calyces are dilated but fibrosis surrounding the pelvis usually prevents gross dilatation. 
In patients with renal mass who have urolithiasis and obstruction or infection, XGP is an important differential diagnosis along with renal cell carcinoma. In one of our cases, both co-existed and thus making it even more problematic. Another case was associated with transitional cell carcinoma of the renal pelvis. Additionally, Akhtal et al have reported XGP in the native kidneys in renal transplant recipients. 
Usually, about one third of the patients with XGP have sterile urine. In our cases, all urine cultures were negative, probably because patients had received long-term antibiotics and/or because of complete obstruction. In more than 40%, E. coli was cultured from intra-operatively obtained pus. Hepatic dysfunction, with elevated liver enzymes, occurs in 20% to 40% of patients with diffuse XGP. , This hepatic dysfunction is usually reversible and liver enzymes return to normal after nephrectomy.
CT Scan is probably the most valuable radiological technique in evaluating patients with XGP, since it helps establish the differentiation of the renal mass and also, determines the involvement of adjacent organs. On CT Scan, about 44% of the cases with XGP show densities between 0 and 75 Haunsfield units. 
Fistula formation is a rare occurrence in XGP. We found one case of reno-colonic fistula. Another unusual complication of XGP encountered in our series was reno-cutaneous fistula. Diabetes mellitus was not a significant predisposing factor in our study. The treatment of choice of XGP is nephrectomy.
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Department of Urology, Jeddah Kidney Center, King Fahd Hospital, P.O. Box 11076, Jeddah 21453
[Figure - 1], [Figure - 2]
[Table - 1]