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

Abstract

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.

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

“…Debate exists regarding medical management of XGP due to potential for malignancy [ 21 ]. A few case reports describe non-operative medical management of XGP with antibiotics alone [ 9 , 82 , 83 ]; though there are also reports of patients proceeding to nephrectomy after failure of medical management [ 80 ]. Upasani and colleagues reported a case of a 17 year old male with XGP who underwent embolization of the renal artery to devascularize the involved renal parenchyma and ablate the infected portion to avoid repeat surgery after initial attempts at nephrectomy failed [ 7 ].…”

“…It most commonly affects middle aged women, and typically presents in the setting of large obstructing renal calculi in both adults and children [ 1 , 3 , 4 ]. XGP has been documented in approximately 16% of pediatric nephrectomy specimens [ [5] , [6] , [7] , [8] , [9] ].…”

“…There are two main variants of XGP: diffuse XGP, which is seen in about 75–90% of all cases, and focal XGP, which is more commonly observed in children [ [9] , [10] , [11] ]. The diffuse form involves the entire kidney while the focal form is isolated to a single segment or pole; most commonly the lower pole [ 12 ].…”

“…The diffuse form involves the entire kidney while the focal form is isolated to a single segment or pole; most commonly the lower pole [ 12 ]. Focal XGP has also been termed “pseudo-tumoral” as it often mimics renal tumors (eg, Wilms tumor, clear cell carcinoma), and histopathology is necessary to obtain an accurate diagnosis [ 9 , 13 ].…”

Xanthogranulomatous pyelonephritis in neonate: presentation, management and outcome

“…The age of onset varies (21 days to 16 years), although 60%–75% of cases have been diagnosed before 5 years of age 2. Neonatal cases are exceptionally rare, with only two cases reported in the literature 3 4. The pathomechanism of XGP is poorly understood.…”