[Xanthogranulomatous pyelonephritis : bear paw sign]. / L'image du mois. Pyélonéphrite xanthogranulomateuse : signe de la patte d'ours.

We present the pathognomonic image of the «bear paw sign¼ of xanthogranulomatous pyelonephritis, a rare form of chronic pyelonephritis typically occurring in association with obstructive uropathy (especially with staghorn calculi) and recurrent urinary tract infections.

Nous présentons l'image pathognomonique du «signe de la patte d'ours¼ de la pyélonéphrite xanthogranulomateuse, forme rare de pyélonéphrite chronique survenant classiquement sur un terrain associant une uropathie obstructive (en particulier sur lithiase coralliforme) et des infections urinaires à répétitions.

Xanthogranulomatous Pyelonephritis: A pooled quantitative analysis of published cases.

Xanthogranulomatous Pyelonephritis (XGP) is a serious and rare inflammatory disease of unknown etiology. This systematic review analyzes XGP cases. We performed a literature search for "Pyelonephritis, Xanthogranulomatous." The primary composite outcome was recovery with post-surgery complications, partial recovery, death, or chronic kidney disease. The secondary outcome was any presentation or treatment complication. Predictor variables consisted of demographics, history, symptoms, and diagnosis/management. Among the 251 patients, the mean age was 36.1 years, and 57.4% were female. The most common symptom and finding were fever (55.0%) and renal stones (53.8%), respectively. There were 15.5% with the composite outcome. There were 51.0% with any presentation or treatment complication. Multivariate logistic regression analysis for the composite outcome showed that kidney of both/horseshoe (OR:3.86, 95% CI:1.01, 14.73, p = 0.048), dialysis required (OR:8.64, 95% CI:2.27, 32.94, p = 0.002), and operative treatment of nephrostomy or nephrostomy followed by nephrectomy (OR:4.57, 95% CI:1.58, 13.17, p = 0.01) were each significantly associated with increased odds. Fever (OR:3.04, 95% CI:1.63, 5.67, p <0.001) and renal stones (OR:2.55, 95% CI:1.35, 4.81, p = 0.004) were each significantly associated with increased odds for any presentation/treatment complication. In conclusion, XGP patients with involvement of both or horseshoe kidneys, dialysis requirements, or treatment of nephrostomy or nephrostomy followed by nephrectomy may require aggressive treatment to mitigate poor patient outcomes.

Xanthogranulomatous Pyelonephritis: Case Report.

BACKGROUND: In the emergency department (ED), pyelonephritis is a fairly common diagnosis, especially in patients with unilateral flank pain. Xanthogranulomatous pyelonephritis (XGP) is a rare type of pyelonephritis that is associated with unique features, which may lead to its diagnosis. CASE REPORT: A 30-year-old male patient presented to the ED for evaluation of right-sided abdominal pain that has been ongoing for the past 24 hours. He noted the pain was located predominantly in the right flank and described it as sharp in nature. The pain was nonradiating and was associated with scant hematuria. He stated that he had similar pains approximately 1 month earlier that resolved after a few days. The patient underwent a bedside ultrasound and a subsequent computed tomography (CT) scan of the abdomen and pelvis, which showed an enlarged, multiloculated right kidney with dilated calyces and a large staghorn calculus, findings that represent XGP. WHY SHOULD AN EMERGENCY PHYSICIAN BE AWARE OF THIS?: This case report highlights an unusual variant of pyelonephritis, a relatively common ED diagnosis. XGP should be considered in patients with recurrent pyelonephritis, as treatment for XGP may require surgical intervention in addition to traditional antibiotic management.

Perioperative outcomes and risk factors for major complications associated with nephrectomy for Xanthogranulomatous pyelonephritis: a multicenter study.

PURPOSE: To determine the risk factors associated with major complications in patients with histologically confirmed Xanthogranulomatous pyelonephritis (XGP) who underwent nephrectomy. METHODS: A multicenter retrospective study was performed including patients who underwent nephrectomy between 2018 and 2022 with histopathological diagnosis of XGP. Clinical and laboratory parameters at the initial presentation were evaluated. Data on extension of XGP was recorded as per the Malek clinical-radiological classification. Characteristics of nephrectomy and perioperative outcomes were obtained. The primary outcome was major complications, defined as a CD ≥ grade 3 and the need for intensive care unit (ICU) admission. Secondary outcomes included the comparison of complications evaluating the nephrectomy approach (transperitoneal, retroperitoneal, and laparoscopic). A sub-analysis stratifying patients who needed ICU admission and Malek classification was performed. RESULTS: A total of 403 patients from 10 centers were included. Major complications were reported in 98 cases (24.3%), and organ injuries were reported in 58 patients (14.4%), being vascular injuries the most frequent (6.2%). Mortality was reported in 5 cases (1.2%). A quick Sepsis-related Organ Failure Assessment (qSOFA) score ≥ 2, increased creatinine, paranephric extension of disease (Malek stage 3), a positive urine culture, and retroperitoneal approach were independent factors associated with major complications. CONCLUSION: Counseling patients on factors associated with higher surgical complications is quintessential when managing this disease. Clinical-radiological staging, such as the Malek classification may predict the risk of major complications in patients with XGP who will undergo nephrectomy. A transperitoneal open approach may be the next best option when laparoscopic approach is not feasible.

Metastatic xanthogranulomatous pyelonephritis managed with immunosuppression.

A male aged in his mid-60s was diagnosed with xanthogranulomatous pyelonephritis after a left nephrectomy for a renal mass that was detected during the investigation of weight loss and drenching night sweats. Past medical history includes type 2 diabetes mellitus, transient ischaemic attack, hypertension, non-alcoholic fatty liver disease, dyslipidaemia, osteoarthritis and active smoking. Three years after the initial diagnosis, the patient represented with abdominal pain. CT imaging demonstrated new pulmonary and pancreatic lesions, which were histologically confirmed to be xanthogranulomatous disease. The patient was too unstable for surgical intervention so was commenced on glucocorticoids with marked improvement in his clinical condition with resolution of inflammatory markers and radiographic improvement. Weaning of prednisolone led to a relapse of disease, which was managed with re-introduction of high-dose prednisolone and the initiation of azathioprine. The patient is now 2 years post initiation of immunosuppressive therapy with stable renal function and no active inflammation.

Lung abscess with chronic cough secondary to xanthogranulomatous pyelonephritis: A rare case report.

RATIONALE: Xanthogranulomatous pyelonephritis (XGPN) is a form of chronic pyelonephritis caused by chronic calculus obstruction and bacterial infection, leading to the destruction of the renal parenchyma and calyces. Conservative treatment is usually not sufficient, and surgical intervention is still the main curative approach. XGPN with transdiaphragmatic extension and lung abscess formation is a rare condition. PATIENT CONCERNS: We report a 64-year-old woman who presented with persistent productive cough. DIAGNOSES: Lung abscess secondary to XPGN. Both nephrostomy urine and sputum cultures showed Proteus mirabilis infection with the same antibiotic sensitivity spectrum, but blood culture was negative. INTERVENTIONS: Laparoscopic radical nephrectomy and prolonged antibiotic treatment. OUTCOMES: The lung abscess and cough gradually resolved in 1 month after nephrectomy. CONCLUSION: Lung abscess secondary to transdiaphragmatic extension of XGPN is rare but should be considered in patients with lower lung infections that are unresponsive to treatment, especially infections due to unusual respiratory pathogens such as P mirabilis.

Xanthogranulomatous pyelonephritis with polycystic kidney disease as a mimic of cystic renal cell carcinoma: a case report.

BACKGROUND: Xanthogranulomatous pyelonephritis (XGP) is a rare chronic pyelonephritis that often mimics other renal diseases, when combined with autosomal dominant polycystic kidney disease(ADPKD), preoperative diagnosis is exceedingly difficult. It is important for clinicians to be aware of an XGP with ADPKD since a misdiagnosis can lead to unnecessary surgical intervention. CASE PRESENTATION: Here, we report a case of a 66-year-old female with a history of bilateral ADPKD and urinary tract infection admitted to our hospital due to right flank pain, feeble, and low-grade fever. Contrast-enhanced ultrasound revealed a malignant mass of the right kidney suspected to be a cystic renal cell carcinoma with polycystic kidney disease. In addition, contrast-enhanced computed tomography (CT) and fluorine 18 fluorodeoxyglucose PET/CT (18F FDG PET/CT) showed similar results. Subsequently, the patient underwent a right radical nephrectomy, but histopathological examination revealed XGP with ADPKD. On the follow-up, the patient's symptoms were relieved. CONCLUSIONS: XGP should be kept in mind during the differential diagnosis of renal masses with ADPKD even in the absence of characteristic clinical symptoms and imaging manifestations.

Xanthogranulomatous pyelonephritis - A diagnostic and therapeutic dilemma.

Xanthogranulomatous pyelonephritis (XGP) is a rare variant of chronic pyelonephritis, occurring in the setting of obstructive uropathy and recurrent urinary tract infections (UTIs). It is difficult to diagnose as it can be asymptomatic until late-stage disease. Localized symptoms such as flank pain and dysuria may be attributed to nephrolithiasis or UTIs without prompting need for further workup. Extrarenal manifestations, most notably fistula formation, may present distal to the kidney and not be readily attributed to a renal pathology. The only known definitive therapy is nephrectomy. A delay in diagnosis can lead to fulminant complications or a more technically difficult nephrectomy. We present three cases of XGP, which serve to highlight the possibility of earlier diagnosis and resultant management options, including the potential for nephron-saving strategies. Early clinical and radiologic suspicion through awareness of risk factors may play an important role in preventing disease progression, avoiding late-stage complications, and improving treatment outcomes.

Clear Cell Renal Cell Carcinoma with Immunotherapy Effect Mimicking Xanthogranulomatous Pyelonephritis.

Renal cell carcinoma is now increasingly treated with checkpoint inhibitor therapy, predominantly in the metastatic setting or occasionally in the adjuvant setting; however, there is little published histopathology data demonstrating the post-therapy features of renal cell carcinoma tumor tissue. We report a middle-aged man, who was undergoing treatment with pembrolizumab for locally recurrent cutaneous basal cell carcinoma and was incidentally found to have a renal mass. Radical nephrectomy demonstrated a 5.0 cm renal mass with extensive xanthogranulomatous features, mimicking xanthogranulomatous pyelonephritis. However, rare clusters of cells demonstrated gland-like lumina, clear cytoplasm, and slightly increased atypia, suggesting scant residual renal cell carcinoma cells. Immunohistochemistry demonstrated focal positivity for pan-keratin and keratin 8/18, EMA, PAX8, CD10, and carbonic anhydrase 9 (CA9), supporting a diagnosis of renal cell carcinoma with extensive treatment response, to the point that it mimicked xanthogranulomatous pyelonephritis. This report demonstrates the histologic features of post-immunotherapy renal cell carcinoma, aiding pathologists in recognition of this phenomenon, which may be misdiagnosed as an inflammatory process, if immunotherapy was performed for other reasons.

Xanthogranulomatous pyelonephritis: a systematic review of treatment and mortality in more than 1000 cases.

OBJECTIVES: To systematically review the current demographics, treatment and mortality rate associated with xanthogranulomatous pyelonephritis (XGP) and to test the hypothesis that the weighted pooled peri-operative mortality rate will be <10%. METHODS: Searches were performed of the Cochrane, Embase and Medline databases and the grey literature for studies published during the period 1 January 2000 to 30 August 2021. Eligible studies reported cohorts of ≥10 predominantly adult patients with XGP and described either average patient age or mortality rate. RESULTS: In total, 40 eligible studies were identified, representing 1139 patients with XGP. There were 18 deaths, with a weighted pooled peri-operative mortality rate of 1436 per 100 000 patients. The mean age was 49 years, 70% of patients were female and 28% had diabetes mellitus. The left kidney was more commonly affected (60%). Four patients had bilateral XGP, and all of whom survived. Renal or ureteric stones were present in 69% of patients, including 48% with staghorn calculi. Urine culture was positive in 59% of cases. Fistulae were present in 8%. Correct preoperative diagnosis occurred in only 45% of patients. Standard treatment continues to comprise a short cause of antibiotics and open radical (total) nephrectomy. Preoperative decompression occurred in 56% of patients. When considered at all, laparoscopic nephrectomy was performed in 34% of patients. Partial nephrectomy was conducted in 2% of patients. CONCLUSIONS: Xanthogranulomatous pyelonephritis has a lower mortality rate than historically reported. A typical patient is a woman in her fifth or sixth decade of life with urolithiasis. While open radical nephrectomy remains the most common treatment method, laparoscopic, and to a lesser degree partial nephrectomy, are feasible in well selected patients.

Perioperative predictors for complications in patients with Xanthogranulomatous Pyelonephritis treated with nephrectomy.

INTRODUCTION: Xanthogranulomatous pyelonephritis is an inflammatory disease characterized by chronic obstruction and infection. This pathology is a life-threatening condition when surgical treatment is carried out. We decided to retrospectively evaluate whether there were perioperative factors that predict complications in patients who undergo nephrectomy. METHODS: We reviewed all nephrectomies done in the period of 2013-2018, in a tertiary referral Hospital with the histopathological diagnosis of Xanthogranulomatous Pyelonephritis. RESULTS: The presence of renal abscess at admission was observed as a risk factor associated with perioperative complications (p = 0.002), presence of abscess was observed in 47.4% of subjects without complications compared to 89.3% of the perioperative complication group. Higher rates of blood transfusion requirement were observed in the perioperative complication group, 89.3% compared to 68.4% (p = 0.029), furthermore, perioperative bleeding was slightly greater in the complication group compared to its counterpart, 700 mL, and 600 mL, respectively (p = 0.01). CONCLUSIONS: Anemia and the presence of abscess were important perioperative factors that predict perioperative complications.

Xanthogranulomatous pyelonephritis: a review and meta-analysis with a focus on management.

PURPOSE: Xanthogranulomatous pyelonephritis (XGP) is a rare form of pyelonephritis more commonly seen in females and diabetics. Frequently associated with renal tract calculi, it is often difficult to diagnose, as it can clinically and radiologically mimic other disorders. Most cases are treated with antibiotics and nephrectomy. The aim of our review is to summarise and analyse the current evidence focusing on management. METHODS: A literature search was conducted to identify papers relating to xanthogranulomatous pyelonephritis in adults. Studies containing ten or more patients with XGP were included for descriptive analysis, and a meta-analyses of cohort studies conducted comparing open and minimally invasive nephrectomy undertaken. Other papers were included for narrative review. RESULTS: 52 studies were identified, 20 were included for narrative review and 32 retrospective observational studies containing 868 patients were included for descriptive analysis. 99.8% of patients underwent nephrectomy, about one-third laparoscopically. The most commonly cultured organisms were Escherichia coli and Proteus mirabilis. 60% of patients, where reported, underwent preoperative drainage. Seven studies containing 211 patients were included for meta-analysis which found that postoperative complications, length of stay and transfusion requirements were all significantly reduced in those who underwent minimally invasive surgery. CONCLUSION: The mainstay management of XGP is antibiotic therapy and nephrectomy. Some studies highlight a role for preoperative upper urinary tract drainage, but evidence supporting this is limited. We present the first meta-analyses examining operative approach for patients undergoing nephrectomy for XGP. Though limited by the data available, our meta-analysis indicates minimally invasive nephrectomy for XGP provides better postoperative outcomes.

Incidentally found focal xanthogranulomatous pyelonephritis with extensive venous thrombus.

A 71-year-old woman with history of asthma presented with 2 months history of shortness of breath; on imaging an incidental left renal mass was noted. Subsequent renal protocol CT was obtained that showed a 4.5 cm left upper pole exophytic mass with renal vein thrombus extending into the inferior vena cava to the level of the caudate lobe concerning for renal cell carcinoma. She underwent an open left radical nephrectomy and IVC thrombectomy with subsequent postoperative pathology demonstrating xanthogranulomatous pyelonephritis without renal cell carcinoma.

Xanthogranulomatous pyelonephritis in a pediatric patient.

INTRODUCTION: Xanthogranulomatous pyelonephritis consists of a chronic infectious and inflammatory process of the renal parenchyma, a variant of chronic obstructive pyelonephritis. It is more prevalent in middle-aged adults, rare in pediatric patients, with less than 300 cases reported in children worldwide. REPORT: Preschooler, aged 2 years and 11 months, male, with 2 months of abdominal distention, increased temperature and intense pallor, associated with microcytic anemia refractory to the use of ferrous sulfate. 1 week before, he had a bulging in his left flank and a hard palpable mass there. Imaging exams (ultrasound and tomography) revealed an overall enlargement of the left kidney, destruction of the renal parenchyma and intense calyceal dilation, forming the "bear's paw" sign, with a staghorn calculus in the pelvis. He underwent treatment with antibiotic therapy and total nephrectomy, with a specimen sent for pathological examination. DISCUSSION: a disease of uncertain incidence in the pediatric age group, xanthogranulomatous pyelonephritis is more prevalent in male children and affects mainly the left kidney, being frequently associated with the presence of stones. Clinically, it has nonspecific symptoms, the most common being abdominal distension and asthenia. Laboratory exams shows microcytic, leukocytosis, thrombocytosis and increased inflammation, pyuria, hematuria and proteinuria, in addition to bacterial growth in urine culture. The diagnosis is anatomopathological, but it can be hinted by contrasted CT scan, with the classical sign of the "bear's paw". Treatment may include nephrectomy and broad-spectrum antibiotic therapy.

Malakoplakia and xanthogranulomatous pyelonephritis treated with nephrectomy: A case report.

RATIONALE: Malakoplakia and xanthogranulomatous pyelonephritis are chronic inflammatory conditions of the kidney characterized by the infiltration of inflammatory cells. PATIENT CONCERNS: An 82-year-old female patient had a history of hypertension, type 2 diabetes mellitus, dyslipidemia, and end-stage renal disease under hemodialysis. She was admitted repeatedly 4 times within 4 months due to urosepsis. DIAGNOSIS: The enlarged right kidney with a low-density lesion at the right middle calyx, and a well-enhanced ureter were noted on the computed tomography scan. Therefore, xanthogranulomatous inflammation was suspected. Semi-rigid ureteroscopy with biopsy was performed, and xanthogranulomatous inflammation of the ureter was confirmed on the pathology report. INTERVENTIONS: After right open radical nephrectomy was performed, the final pathology report revealed malakoplakia with xanthogranulomatous pyelonephritis. OUTCOMES: After the surgery, she has no longer suffered from urosepsis for 8 months, and there were no adverse event or recurrence noted. LESSONS: With this case report, we aim to emphasize that these 2 diseases are not mutually exclusive, but they may exist simultaneously in the same patient.