[A Case of Xanthogranulomatous Pyelonephritis with Multiple Lymphadenopathy that was Difficult to Differentiate from Renal Tumor].

A 74-year-old woman presented to our hospital with the main complaint of anorexia and weight loss for several months. Computed tomography (CT) revealed right urinary stone, hydronephrosis, multiple lymphadenopathy, and a mass in the right kidney. Considering these findings, she was suspected to have renal malignancy (kidney or renal pelvis cancer) with multiple lymph node metastases; therefore, nephrectomy was performed. Her pathological diagnosis was xanthogranulomatous pyelonephritis (XGPN). There was no postoperative renal function decline, and multiple lymphadenopathy also disappeared on CT 3 months after surgery. It was judged to be reactive swelling due to inflammation. XGPN is a pathological condition characterized by accumulation of mast cells and activated macrophages in the renal tissue; and, the renal tissue recognizes yellowish granulation growth because of repeating pyelonephritis due to urinary tract passing impairment. In some cases, it is difficult to differentiate XGPN from renal malignancy. Moreover, lymphadenopathy may be lymph node metastasis but may also present reactive enlargement due to the effect of inflammation, making it even more difficult to differentiate when accompanied by lymphadenopathy. We report this case in which it was difficult to differentiate XGPN from renal malignancy considering the scarcity of reports of XGPN accompanied by multiple lymphadenopathy.

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.

Squamous cell carcinoma of the renal pelvis masquerading as xanthogranulomatous pyelonephritis.

We report a rare case of a 56-year-old male with a history of hypertension who initially presented to the emergency department with abdominal pain and was radiologically diagnosed with left xanthogranulomatous pyelonephritis (XGP) in a non-functioning kidney with a staghorn calculus. Pathological evaluation of his kidney revealed squamous cell carcinoma (SCC) of the renal pelvis with invasion into the renal parenchyma. We highlight the presentation, diagnosis, and management of this rare condition.

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.

Imaging Characterization of Renal Masses.

The detection of a renal mass is a relatively frequent occurrence in the daily practice of any Radiology Department. The diagnostic approaches depend on whether the lesion is cystic or solid. Cystic lesions can be managed using the Bosniak classification, while management of solid lesions depends on whether the lesion is well-defined or infiltrative. The approach to well-defined lesions focuses mainly on the differentiation between renal cancer and benign tumors such as angiomyolipoma (AML) and oncocytoma. Differential diagnosis of infiltrative lesions is wider, including primary and secondary malignancies and inflammatory disease, and knowledge of the patient history is essential. Radiologists may establish a possible differential diagnosis based on the imaging features of the renal masses and the clinical history. The aim of this review is to present the contribution of the different imaging techniques and image guided biopsies in the diagnostic management of cystic and solid renal lesions.

[Xanthogranulomatous Pyelonephritis after Partial Nephrectomy Mimicking the Local Recurrence of Papillary Renal Cell Carcinoma].

A 55-year-old man underwent right partial nephrectomy and was diagnosed with papillary type 1 renal cell carcinoma (RCC), pT1a. The surgical margin was negative. Six months later, a follow-up computed tomography scan revealed that a mass appeared adjacent to the location of resection. There were no symptoms nor abnormal blood chemistry results at that time. The possibility of local recurrence of RCC could not be ruled out with by magnetic resonance imaging. Radical nephrectomy was performed for suspected rapid recurrence of RCC. Pathological diagnosis was xanthogranulomatous pyelonephritis but not malignancy.

Symmetric nephromegaly.

We report a lady with bilateral symmetrical xanthogranulomatous pyelonephritis (XPGN) presented with acute kidney injury and sepsis, in which both CT and MRI mimicked an infiltrative disease, except that the infiltration was not very homogenous. Eventually, the pathological diagnosis turned out to be XPGN. Most XPGN were unilateral, and there have been a few publications of bilateral involvement. Moreover, this case lacked typical manifestations, such as renal calculus, contracted renal pelvis, or obstructive nephropathy. This image reminds us that bilateral renal infiltrative disease could not completely exclude the possibility of XPGN, in which the inhomogeneity of the infiltration pattern on CT/MRI may be a clue.

Nephron-sparing management of Xanthogranulomatous pyelonephritis presenting as spontaneous renal hemorrhage: a case report and literature review.

BACKGROUND: Xanthogranulomatous pyelonephritis (XGP) is an uncommon infectious disease of the kidney known to mimic other renal maladies. A rare presentation of this uncommon disease is spontaneous renal hemorrhage (SRH). CASE PRESENTATION: We report a case of XGP in a 58 year old woman who presented with abdominal pain, hematuria, and radiating left flank pain. CT scan was felt to be consistent with perirenal hemorrhage abutting a fat-containing renal mass. The patient was eventually taken to surgery for left partial nephrectomy. Pathology report returned as XGP, and the patient has no complications from this disease process at 8 month follow up. CONCLUSION: Our search of the literature shows XGP presenting as SRH to be a rare clinical entity. Furthermore, this is the first such case managed with a nephron-sparing approach. The "great imitator" XGP should be added to the differential for patients presenting with spontaneous renal hemorrhage.

Xanthogranulomatous Pyelonephritis: A Complicated Febrile Urinary Tract Infection Detected by Point-of-Care Ultrasound in the Emergency Department.

BACKGROUND: Febrile urinary tract infections (UTIs) include a spectrum of pathologies from uncomplicated pyelonephritis to urosepsis, including xanthogranulomatous pyelonephritis (XGP). Most febrile UTIs are treated with antibiotics alone, but studies indicate nearly 12% of cases of presumed simple pyelonephritis require emergent urologic intervention. How to identify these individuals, while limiting unnecessary advanced imaging and delays in diagnosis, challenges all emergency providers. We review the diagnosis and management of XGP, as well as the evidence regarding the role of renal ultrasound in the identification of complicated presentations of febrile UTIs. CASE REPORT: We present a case of XGP, a complicated febrile UTI requiring immediate urologic intervention, diagnosed by point-of-care ultrasound. A 40-year-old female presented in severe sepsis and complaining of flank pain. Prompt bedside ultrasound demonstrated hydronephrosis, expediting definitive urologic treatment via percutaneous nephrostomy tube placement. WHY SHOULD AN EMERGENCY PHYSICIAN BE AWARE OF THIS?: With a mortality rate exceeding 40%, obstructed pyonephrosis requires prompt decompression. Given its exceptional sensitivity for identifying hydronephrosis and ability to detect abscesses and emphysematous changes, we advocate a point-of-care ultrasound-first approach to screen for cases of complicated febrile UTIs in order to expedite treatment and limit radiation in uncomplicated presentations.

Extensive renal sinus lipomatosis in xanthogranulomatous pyelonephritis simulating liposarcoma.

Renal replacement lipomatosis is a condition characterized by varying degrees of renal parenchymal atrophy and perirenal fibrofatty proliferation secondary to chronic inflammation such as xanthogranulomatous pyelonephritis. In severe cases, imaging findings can be misdiagnosed as retroperitoneal liposarcoma.

[Xanthogranulonatous pyelonephritis: report of 5 cases].

Xanthogranulomatous pyelonephritis (XGP) is an unusual form of chronic pyelonephritis in which the renal parenchyma is destroyed and replaced by lipid-laden foamy macrophages. It usually affects middle-aged women with a history of recurrent urinary tract infection, diabetes, or kidney stones. The inflammatory process is usually diffuse and can extend beyond the kidney. The rare focal forms may simulate primary renal tumours. The preoperative imaging diagnosis may be difficult. We reported five cases of XGP, The findings of ours were recorded including kidney size, shape, contour, the echogenecity of the renal parenchyma, the internal echoes of the dilate collecting system, the presence of perinephric fluid accumulation and obstruction. One of the 5 cases was a male patient, and the other four were female, with a mean age of 53 years. He affected kidneys of the 5 cases swelled in different degrees, and one of them was found with line-like anechoic fluid. Among the 5 cases, one kidney appeared as diffusely reducing of the parenchyma echogenicity, multiple hypoechoic areas, disappearance of corticomedullary differentiation and multiple hyperecho with shadow. A round cystic anechoic lesion was found in one kidney, with internal punctate echo and peripheral fluid. Ultrasonographic finding of 1 case was extremely hypoechoic lesion on the left kidney, protruding from the outline of the kidney, with the partial renal capsule discontinuous, the less clear boundary, and a little blood flow in it. Ultrasonographic demonstration of 2 cases was mild dilatation of the collecting system with irregular wall thickening and internal hypoechogenicity, and 1 case was solid lesion with less clear boundary to the pelvic wall and a small amount of blood flow signal, the another 1 case was showed floccule without internal blood flow. Three cases were caused by chronic obstruction verified by operation, of which one was staghorn calculi, one was poorly differentiated squamous cell carcinoma in the middle part of the ureter, and one was inflammatory stricture of upper ureteral. Through analysis of the above five cases and review of related literature, we explored diagnoses and management of the patients with XGP. Xanthogranulomatous pyelonephritis (XGP) is a rare chronic variant of pyelonephritis characterized by destruction of the renal parenchyma. Combining ultrasonographic features of XGP with clinical recurrent urinary infection and chronic obstruction, XGP can be included in the differentiation. The diagnosis of XGP suspected by ultrasound can be clarified by CT, MRI, contrast-enhanced ultrasound.

[Case of xanthogranulomatous pyelonephritis complicated by simultaneous septic pulmonary embolism].

A 57-year-old man with fever-up and multiple nodules in the peripheral area of the lungs on the chest CT was referred to the department of respiratory medicine of our hospital for further examination. The whole body CT disclosed a space-occupying lesion in the left frontal lobe of his brain, an irregular mass in the left kidney, and swelling of paraaortic lymph nodes. A pathological diagnosis could not be made from the results of the bronchoscopic examination and percutaneous needle biopsy for the renal mass. Left nephrectomy and lymph node dissection were carried out because of possible renal malignancy with distant metastases. The renal lesion was diagnosed as xanthogranulomatous pyelonephritis histopathologically. After the nephrectomy, the multiple lung nodules disappeared spontaneously leaving scars in some lesions. Septic pulmonary embolism was highly suspected on the basis of the clinical course. The brain nodule also decreased in size significantly and is currently under careful surveillance.

Systemic Amyloid A Amyloidosis Secondary to Xanthogranulomatous Pyelonephritis.

The combination of systemic amyloid A (AA) amyloidosis and xanthogranulomatous pyelonephritis (XGP) resulting from a chronic urinary tract infection is extremely rare. We herein report a case of systemic AA amyloidosis secondary to XGP for which clinical remission developed after nephrectomy. To our knowledge, this is the first case report describing the clinical improvement of systemic AA amyloidosis secondary to XGP after nephrectomy in Japan. Clinicians should be aware of this uncommon combination and search for amyloid depositions in cases of XGP.

I saw the "bear paw" sign - Massive renal xanthogranulomatous pyelonephritis.

The bear paw sign is a radiologic sign seen on computed tomography (CT) that indicates the development of xanthogranulomatous pyelonephritis (XGP). It refers to the multiple, rim-enhancing, low attenuation renal collections seen in the diffuse form of XGP. The term "bear paw" sign first appeared in the literature in 1989 and has since been widely used to describe this serious, but treatable, pathology.

Acute conditions affecting the perinephric space: imaging anatomy, pathways of disease spread, and differential diagnosis.

The perinephric space is an important, central compartment of the retroperitoneum which may host various acute conditions. Imaging evaluation of the perinephric space requires an understanding of its anatomy and the pathways of disease spread to and from other retroperitoneal compartments. Numerous acute conditions can affect the perinephric space and may occur in isolation, extend from nearby retroperitoneal structures, or be part of a systemic condition. Familiarity with the key imaging findings of acute conditions affecting the perinephric space is imperative to facilitate diagnosis and guide treatment. The purpose of this article is to review and illustrate the relevant anatomy, pathways of disease spread, and acute pathology encountered during cross-sectional imaging evaluation of the perinephric space.

Neonatal Urinary Tract Infection and Renal Nodular Lesion: A Rare Case of Xanthogranulomatous Pyelonephritis.

Xanthogranulomatous pyelonephritis (XPN) is an uncommon variant of chronic pyelonephritis with a poorly understood pathogenesis and a challenging diagnosis. It is rare in pediatric patients, particularly in the neonatal period. We report the case of an 18-day-old female neonate admitted to the emergency room due to macroscopic hematuria and poor feeding. Urinalysis revealed leukocyturia and she was initially admitted under the clinical suspicion of acute pyelonephritis. Renal ultrasound and magnetic resonance imaging (MRI) revealed a progressive nodular lesion in the middle third of the left kidney. Given the suspicion of renal abscess or neoplasm, the patient was transferred to our tertiary hospital. Urinary catecholamines and tumor markers had normal values. Percutaneous kidney biopsy confirmed XPN. Posterior computed tomography scan excluded extension to neighboring structures. A conservative management with systemic antibiotic therapy was decided. She completed 7 weeks of systemic antibiotic therapy (ampicillin and cefotaxime) with progressive reduction of lesion size and posterior calcification. Follow-up at 3 years was uneventful. The lipid profile and study of neutrophil function were normal. Voiding cystourethrography excluded vesicoureteral reflux. The authors intend to highlight the importance of a high index of suspicion of XPN to allow preoperative diagnosis. Histopathological assessment is mandatory to confirm XPN and exclude other entities mimicked by focal and unilateral progressive disease. There are only a few published cases of optimal clinical evolution solely with broad-spectrum antibiotics; however, this may allow a beneficial nephron-sparing approach in selected patients.

Focal Xanthogranulomatous Pyelonephritis on FDG PET/CT.

ABSTRACT: Xanthogranulomatous pyelonephritis is a rare disease that was often accompanied with urinary obstruction. The focal form of xanthogranulomatous pyelonephritis is frequently misdiagnosed as malignancy. Here we present FDG PET/CT findings of a case focal xanthogranulomatous pyelonephritis in a 66-year-old woman with polycystic liver and kidney disease. The image showed a polycystic mass in the inferior pole of right kidney with high FDG uptake in the cystic wall, which was suggestive of a cystic renal carcinoma. Right radical nephrectomy was subsequently performed. The postsurgical pathology revealed xanthogranulomatous pyelonephritis.