Xanthogranulomatous pyelonephritis presenting as a pseudotumor in a 2-month-old boy

A pediatric case of xanthogranulomatous pyelonephritis in the setting of Covid-19 and multi-system inflammatory syndrome (MIS-C)

Xanthogranulmatous pyelonephritis is a rare, chronic inflammatory pathology of the kidney. It most commonly arises in middle-aged females, but there are case reports and series described in the pediatric population. Here, we discuss the case of a 14 year old male who presented with xanthogranulomatous pyelonephritis in the setting of Covid-19 and multi-system inflammatory syndrome (MIS-C). As xanthogranulomatous pyelonephritis often mimics other diseases that are more prevalent in the pediatric population, our case was only definitively diagnosed with histopathology after surgical resection. This report is novel in that, to our knowledge, it is the first to describe xanthogranulomatous pyelonephritis in the setting of MIS-C.

[Abdominal mass revealing xanthogranulomatous pyelonephritis in an infant]

Xanthogranulomatous pyelonephritis (XGP) is a chronic pyelonephritis observed in children and exceptionally in infants. Symptomatology is vague and may delay diagnosis and patient's management. Treatment is based on medical therapy but most often on surgery with poor renal prognosis. We report the case of a 15-month old infant with isolated mass in the left flank. He had no fever or alteration of general state and urine cultures were sterile. Radiological evaluation (renal ultrasound, uroscan and renal scintigraphy) highlighted left non-functioning kidney with "hydropyonephrosis" evoking the diagnosis of XGP. The indication for total nephrectomy by lombotomy was posed and definitive anatomo-pathological examination confirmed the diagnosis of diffuse XGP. This observation emphasizes the importance of suspect PXG in patients with renal mass or malformative uropathy with recurrent urinary tract infections whose treatment should be rigorous and codified.

Xanthogranulomatous pyelonephritis mimicking a renal cell carcinoma: a unique and challenging case

We describe an unusual case of xanthogranulomatous pyelonephritis (XGPN) in a 73-year-old woman diagnosed after a blunt abdominal trauma. This case is unique because of the atypical presentation, with absence of symptoms, normal laboratory exams, and unusual computed tomography and magnetic resonance imaging findings. The patient underwent radical nephrectomy because a renal cystic tumor was suspected. Only the histopathological findings suggested the final diagnosis of XGPN.

[Diffuse xanthogranulomatous pyelonephritis in infant]

We report a case of a renal mass in a 4-month boy, which occured during the assessment of a pelvi-calyceal dilatation diagnosed at 23 weeks of gestational age. There was no history of urinary infection, fever or weight loss. Physical examination revealed a mass of the left flank with significant flank tenderness. Laboratory test showed a biological inflammatory syndrome and urine culture was negative. Investigations including ultrasound and computed tomography scan were suggestive of diffuse xanthogranulomatous pyelonephritis with a non-functioning left kidney. Left total nephrectomy was performed through a lumbar incision with an extraperitoneal approach. The kidney was enlarged with a dilated pelvis containing pus upstream of a proximal ureteral atretic segment. Pathological examination of the kidney confirmed the diagnosis of diffuse xanthogranulomatous pyelonephritis. The boy remains well at 1 year follow-up. Xanthogranulomatous pyelonephritis is very rare in infants. It is an uncommon severe progressive renal infection resulting in destruction of renal parenchyma, histologically replaced by xanthomatous cells and granulomatous reaction. Pathogenesis of xanthogranulomatous pyelonephritis remains unclear. But it is well known that urinary tract obstruction and renal lithiasis are determining factors. It can occur in variant clinical forms but its symptoms remain non-specific. Curative treatment consists in nephrectomy and definitive diagnosis is made on histological examination of the kidney. This diagnosis should be discussed when a renal mass occurs in a context of malformative uropathy and xanthogranulomatous pyelonephritis have to be included in the differential diagnosis of renal mass in infants and children.

Xanthogranulomatous Pyelonephritis in Childhood: A Critical Analysis of 10 Cases and of the Literature

OBJECTIVES

To report our experience with 10 cases of pediatric xanthogranulomatous pyelonephritis and review the literature regarding this relatively uncommon disease.

METHODS

The records of 10 patients presenting to our institution with xanthogranulomatous pyelonephritis between 1996 and 2006 were examined. The mode of presentation, clinical and radiologic findings, blood count, blood chemistry, urine culture results, operative findings, and histologic findings of the affected kidney were recorded.

RESULTS

Staging was performed according to the classification of Malek and Elder. Through radiologic and operative investigations our patients were classified as Stage 1 (n = 1), Stage 2 (n = 6), and Stage 3 (n = 3). Simple nephrectomy was performed in all 10 patients.

CONCLUSIONS

Previously the diagnosis of xanthogranulomatous pyelonephritis was normally based on pathologic assessment, most commonly after nephrectomy. During the last decade, however, increasingly sensitive radiologic investigations (sonography, four-phase computed tomography, and magnetic resonance imaging) in combination with clinical suspicion have made its preoperative diagnosis possible. Surgical intervention still remains the cornerstone of treatment for this relatively uncommon disease.

Ultrasonographic features of focal xanthogranulomatous pyelonephritis

OBJECTIVE

To analyze the ultrasonographic features of focal xanthogranulomatous pyelonephritis.

METHODS

Ultrasonographic features of 15 patients with pathologically proved focal xanthogranulomatous pyelonephritis were retrospectively analyzed by 2 radiologists who reached a consensus, in terms of the location, margin, size, and echo texture of the mass, associated calculi, lymphadenopathy, or local extension, in comparison with computed tomographic and clinical findings.

RESULTS

At ultrasonography, 12 (80%) of 15 masses were well circumscribed. The maximal sizes of the masses ranged from 2.5 to 5.8 (mean, 3.8) cm. Thirteen solid masses (87%) were hyperechoic (n = 7), hypoechoic (n = 4), or isoechoic (n = 4) to the renal cortex, and the preoperative diagnosis was either renal cell carcinoma (n = 11) or Wilms tumor (n = 2). The preoperative diagnosis of the other 2 cystic lesions (13%) was renal abscess. Renal calculi were found in 1 case, but lymphadenopathy or local extension was not depicted. Clinical inflammatory signs were found in 11 of 15 patients.

CONCLUSIONS

There were no specific ultrasonographic features that allow for the distinction between focal xanthogranulomatous pyelonephritis and renal tumors or abscesses. Focal xanthogranulomatous pyelonephritis should be considered when there are clinical signs of infection or inflammation and a focal solid mass is seen on ultrasonography.

Pediatric focal xanthogranulomatous pyelonephritis: dynamic contrast-enhanced MRI findings

Xanthogranulomatous pyelonephritis (XPN) is the result of chronic renal infection. It is very rare in childhood and the focal form, which is said to be more common in children, is often misdiagnosed as a renal tumor. We report a case of a focal XPN in a 14-year-old girl. The true preoperative diagnosis may be very hard in children especially in the focal form but it seems to be possible by the help of dynamic contrast-enhanced MRI.