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Xanthogranulomatous Pyelonephritis: Symptoms, Diagnosis and Treatment

Definition of Xanthogranulomatous Pyelonephritis

Xanthogranulomatous pyelonephritis (XP) is a rare form of chronic pyelonephritis with foam cells (large macrophages with foamy lipid-containing cytoplasm), which leads to kidney destruction (Bingol-Kologlu et al., 2002) (Zorzos et al., 2003).

Epidemiology

XP is rare (incidence 1.4/100000). Women are more likely affected than men.

Etiology

XP is usually a unilateral renal disease, which develops in nonfunctioning kidneys with nephrolithiasis, urinary tract infection, and upper urinary tract obstruction. The most commonly isolated bacterial organisms are E. coli, Proteus, Klebsiella, and Staphylococcus.

Pathology of Xanthogranulomatous Pyelonephritis

Gross Pathology:

Typical findings are an enlarged kidney, enlarged renal pelvis filled with pus (pyonephrosis), orange-yellow inflammatory lesions in addition to tissue necrosis, and small abscesses. The renal involvement is limited initially to segments of the kidney; later, the inflammatory process involves most of the kidney. A granulomatous inflammatory tissue replaces the renal parenchyma; the disease may spread into adjacent structures of the retroperitoneum.

Histology:

The inflammatory tissue contains neutrophils, lymphocytes, plasma cells, necrosis, and large macrophages with foamy lipid-containing cytoplasm. Sometimes epitheloid granulomas are found.

Signs and Symptoms of Xanthogranulomatous Pyelonephritis

• Flank pain (70%)
• Fever and chills (70%)
• Flank tumor
• Persistent bacteriuria
• General malaise and weight loss.

Diagnostic Workup

Urine sediment:

Urine sediment shows leukocyturia, bacteriuria, and possibly the detection of foam cells (lipid-laden macrophages).

Urine culture:

Urine culture often reveals bacterial growth but has a low specificity and is not helpful in diagnosis.

Laboratory tests:

Leukocytosis, increased ESR, and increased CRP. Consider blood cultures in patients with fever.

Renal ultrasound:

Renal ultrasound shows an enlarged kidney with a mixed echogenic mass, which is hard to be distinguished from a malignant tumor. Nephrolithiasis is a typical finding.

Computed tomography:

CT scanning is the diagnostic tool of choice. Typical findings are nephrolithiasis, decreased contrast uptake in the surrounding renal tissue (bear paw sign), and hydronephrosis. The inflammatory process may involve the perinephric tissue and, in some cases, renal cell carcinoma cannot be ruled out.

MRI:

MRI is an alternative to CT scanning, especially in patients with renal failure.

Renal scintigraphy:

Perform scintigraphy to clarify the remaining kidney function when organ preservation seems possible.

Intravenous urography:

IVP has only historical value and is now replaced by CT. If done, KUB X-ray may show an increased renal shadow and nephrolithiasis. IVP reveals in 30–80% a missing renal function with no opacification of the affected side.

Treatment of Xanthogranulomatous Pyelonephritis

Standard therapy for xanthogranulomatous pyelonephritis is nephrectomy or rarely partial nephrectomy. Surgery is complex because of adhesions; a laparoscopic approach is not recommended. Perioperative antibiotic therapy is essential, which may be modified after the results of intraoperative swab tests. In individual cases, it was possible to cure segmental XP with antibiotic therapy and internal splinting.

References

Zorzos u.a. 2003 ZORZOS, I. ; MOUTZOURIS, V. ; KORAKIANITIS, G. ; KATSOU, G.: Analysis of 39 cases of xanthogranulomatous pyelonephritis with emphasis on CT findings.
In: Scand J Urol Nephrol
37 (2003), Nr. 4, S. 342–7

  Deutsche Version: Xanthogranulomatöse Pyelonephritis