You are in: eMedicine Specialties > Urology > Infections and Related Inflammatory Conditions Xanthogranulomatous PyelonephritisArticle Last Updated: Jun 11, 2008AUTHOR AND EDITOR INFORMATIONSection 1 of 12
  Author: Joe D Mobley III, MD, MPH, Resident Physician, Department of Surgery, Division of Urology, University of Tennessee Graduate School of Medicine/University of Tennessee Medical Center Joe D Mobley, III, is a member of the following medical societies: American College of Surgeons, American Medical Association, American Urological Association, Endourological Society, and Tennessee Medical Association Coauthor(s): Scott Rutchik, MD, Assistant Professor, Department of Surgery, Division of Urology, University of Connecticut School of Medicine Editors: Gamal Mostafa Ghoniem, MD, FACS, Fellowship Program Director, Clinical Professor of Surgery, Head, Section of Voiding Dysfunction, Female Urology and Reconstruction, Cleveland Clinic Florida; Francisco Talavera, PharmD, PhD, Senior Pharmacy Editor, eMedicine; J Stuart Wolf, Jr, MD, FACS, David A Bloom Professor of Urology, Director, Division of Minimally Invasive Urology, Department of Urology, University of Michigan Medical Center; Bradley Fields Schwartz, DO, FACS, Associate Professor of Urology, Director, Center for Laparoscopy and Endourology, Department of Surgery, Southern Illinois University School of Medicine Author and Editor Disclosure Synonyms and related keywords: xanthogranulomatous pyelonephritis, XGP, infectious renal phlegmon, long-term renal obstruction, renal cell carcinoma, nephrectomy, pyelocutaneous fistulae, ureterocutaneous fistulae, pyeloenteric fistulae INTRODUCTIONSection 2 of 12
  Xanthogranulomatous pyelonephritis (XGP) is a rare, serious, debilitating illness characterized by an infectious renal phlegmon. This disease process ultimately results in focal or diffuse renal destruction and is characterized pathologically by lipid-laden foamy macrophages. XGP shares many characteristics with true renal neoplasms in terms of its radiographic appearance and ability to involve adjacent structures or organs. Most cases of XGP are unilateral and are often associated with urinary tract obstruction, infection, nephrolithiasis, diabetes, and/or immunocompromise. The treatment of XGP is almost universally extirpative and can pose a formidable challenge to the surgeon. History of the ProcedureSchlagenhaufer first described XGP in 1916. The first pediatric case was not described until 1963. Historically, open extirpative therapy has been the hallmark of management, although an increasing number of reports have recently described successful laparoscopic intervention. ProblemXGP is defined as a chronic inflammatory disorder of the kidney characterized by a destructive mass that invades the renal parenchyma. The condition is most commonly associated with Proteus or Escherichia coli infection. Pseudomonas species have also been implicated. The kidney is usually nonfunctional. Most cases of XGP involve a diffuse process; however, up to 20% are focal. Although most cases of XGP are unilateral, bilateral disease has been reported. Bilateral nephrectomy and long-term dialysis is a treatment option. Although Perez et al described successful treatment with partial nephrectomies in one patient,1 bilateral XGP is usually fatal. FrequencyXGP occurs in approximately 1% of all renal infections. Although XGP is rare in the pediatric population, it is found in approximately 16% of pediatric nephrectomy specimens. XGP is 4 times more common in women than in men and is usually noted in the fifth and sixth decades of life. XGP affects both kidneys with equal frequency. EtiologyThe exact etiology of XGP is unknown, but it is generally accepted that the disease process requires long-term renal obstruction and infection. Stones (frequently of staghorn proportions) develop in 80% of patients with XGP but are not required to make the diagnosis. XGP is often observed in patients with diabetes and/or immunocompromise. Abnormal lipid metabolism has also been hypothesized as an etiologic factor in individuals with XGP. PathophysiologyXGP displays neoplasmlike properties capable of local tissue invasion and destruction and has been referred to as a pseudotumor. Adjacent organs, including the spleen, pancreas, or duodenum, may be involved. ClinicalPatients with XGP often appear chronically ill. Symptoms include anorexia, fever, chills, weight loss, and flank pain. The pain of XGP is not colicky in nature; it is usually dull and persistent. Urine typically contains both leukocytes and bacteria. The pH is often basic because Proteus mirabilis is a urease-producing organism. The erythrocyte sedimentation rate is frequently elevated. XGP is notorious for fistulization. Pyelocutaneous and ureterocutaneous fistulae have been well-described. Other organs are occasionally involved in this process, including surrounding viscera with resulting pyeloenteric fistulae. Renal cell carcinoma may be indistinguishable from XGP radiographically and clinically. A case of XGP involving thrombus of the renal vein has been reported.2 XGP and renal cell carcinoma have even been observed in the same specimen. Shah et al have reported a mistaken diagnosis of renal XGP that was subsequently proven to be renal tuberculosis.3 XGP must be diagnosed based on histology rather than based solely on radiographic imaging studies. INDICATIONSSection 3 of 12
Xanthogranulomatous pyelonephritis (XGP) is a surgically managed disease requiring either nephrectomy or, in rare circumstances, partial nephrectomy. Extirpation is necessary because the disease occurs or results in an infected, nonfunctioning kidney. RELEVANT ANATOMYSection 4 of 12
The kidneys are paired organs in the retroperitoneum. They are covered in a thin, fibrous capsule that is in turn covered by Gerota fascia. On the right, the liver and adrenal gland abut the superior pole of the kidney. The second part of the duodenum is medial to the right kidney and may be reflected medially to gain exposure to the inferior vena cava (Kocher maneuver). On the left, the superior pole of the kidney is attached to the spleen superolaterally (splenorenal ligament) and is very near to or in direct contact with the tail of the pancreas medially. The colon is anterior to the kidneys and is easily reflected anteriorly and medially when transabdominal exposure is required. The renal hilar structure from anterior to posterior includes the vein, artery, and collecting system. The left renal vein has 3 draining tributaries, ie, the adrenal, gonadal, and posterior lumbar veins. CONTRAINDICATIONSSection 5 of 12
Contraindications to surgical therapy of xanthogranulomatous pyelonephritis (XGP) are those consistent with all major operations and intolerance to anesthesia, uncorrected coagulopathy, and severe connective-tissue disorders. WORKUPSection 6 of 12
Lab Studies
Imaging StudiesXGP cannot be diagnosed solely based on radiographic findings.
Histologic FindingsThe pathognomonic microscopic feature is the lipid-laden foamy macrophage. These cells can be difficult to distinguish from clear cell carcinoma on frozen section. StagingMalek and Elder have proposed the following stages of XGP involvement:6
TREATMENTSection 7 of 12
Medical therapyMedical therapy has proven sufficient for treatment of xanthogranulomatous pyelonephritis (XGP) in only a handful of cases. Antibiotics may be appropriate as a temporizing measure in patients who require a medical workup prior to nephrectomy. Similarly, appropriate antibiotics should be administered prior to operative intervention. The choice of antibiotic should be geared toward the identity and sensitivity of the organism. Proteus organisms and E coli are usually sensitive to various antibiotics, including first-generation cephalosporins and trimethoprim-sulfamethoxazole. Pseudomonas species have a narrower spectrum to which they are sensitive, however, and may require the use of aminoglycosides, third-generation cephalosporins, or fluoroquinolones. In patients who are not septic and who have been evaluated on an outpatient basis, the author's preference is to use an oral antibiotic until surgery, when intravenous antibiotics may be administered. Guidelines have not been established regarding the duration of antibiotic therapy after nephrectomy, but the author usually continues an active oral agent for 1 week. Surgical therapyNephrectomy is the criterion standard of treatment for XGP. These are often challenging cases, particularly in patients with local organ involvement. The goal is to remove all involved granulomatous tissue. If this is not accomplished, the remaining infected tissue may lead to cutaneous fistulae. Some authors have advocated a role for partial nephrectomy if the disease is limited and therefore amenable to this operation.7 Laparoscopic nephrectomy is feasible for certain cases of XGP. Small pediatric series of XGP have reported success with the laparoscopic technique. However, Bercowsky et al reported that the technical difficulty and associated complications of the procedure negated any benefits over open nephrectomy.8 The increased use of hand-assisted laparoscopic nephrectomy may allow for an acceptable compromise between technical feasibility and acceptable patient morbidity. The laparoscopic approach may be entertained in all cases, but the patient and the patient's family can expect a conversion rate of nearly 50%. Preoperative details
Intraoperative detailsA flank approach through the appropriate intercostal/subcostal subcostal space (often the 11th rib) is desirable to avoid contamination of the peritoneum. Transabdominal subcostal exposure may be unavoidable if adjacent organs are involved with the mass. The basic principles of nephrectomy apply to the extirpation of renal XGP. If possible, a radical nephrectomy (including Gerota fascia) should be performed, since the mass may still represent a neoplasm. All involved tissue must be removed. Liberal irrigation with antibiotic fluid is performed, and a suction drain is left in place. Postoperative detailsThe immediate postoperative care for patients with XGP is consistent with care that follows standard nephrectomy.
Follow-upAnnual imaging of the contralateral urinary tract is important. Aggressively treat all urinary tract infections. If possible, eliminate or control the agent or illness that is predisposing the patient to XGP. Evaluation of lower urinary tract pathology and voiding dysfunction may be important in these patients. COMPLICATIONSSection 8 of 12
The urological surgeon should maintain a low threshold to involve a general surgeon in patients with xanthogranulomatous pyelonephritis (XGP). Bleeding should be aggressively controlled. On the left, splenic injury may result; if possible, preservation of the spleen should be attempted. Any pancreatic injuries must be identified, repaired, and appropriately drained. Similarly, right-sided injuries may occur to the duodenum and liver. Liver lacerations during nephrectomy are frequently limited to capsular tears, which may be easily controlled with argon-beam coagulation and pressure. Duodenal injuries require repair and nasogastric and cutaneous drainage. The colon is vulnerable to injury on either side. A patient who has received adequate bowel preparation may typically have these colonic injuries primarily repaired. Vascular injury, especially on the right side, that involves the inferior vena cava can be humbling. The right-sided processes are often very inflamed and stuck, involving the adrenal and gonadal veins, lending them to avulsion and injury. Great care must be taken when dissecting out the right renal hilum. An alternative is to cross-clamp the hilum, transect it, and oversew the entire bundle. This can be planned or used in an emergency. Postoperative abscess and cutaneous fistulization may occur, often after the drain has been removed and the patient has been discharged from the hospital. Patients typically present with drainage from the wound and fevers. CT scanning and percutaneous drainage should be performed, along with administration of intravenous antibiotics. OUTCOME AND PROGNOSISSection 9 of 12
The overall prognosis for xanthogranulomatous pyelonephritis (XGP) is good. Death from this entity is exceedingly rare, although morbidity is substantial. FUTURE AND CONTROVERSIESSection 10 of 12
MULTIMEDIASection 11 of 12
REFERENCESSection 12 of 12
Xanthogranulomatous Pyelonephritis excerpt Article Last Updated: Jun 11, 2008 | ||||||||||||||||||||||||||
