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.

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.

Xanthogranulomatous pyelonephritis: Case series - Clinical, radiologic, therapeutic, and histological aspects

Purpose

Xanthogranulomatous pyelonephritis (XGP) is a chronic and severe infection of the kidney. We aimed to review the main clinical, imaging, and histological findings and to assess predictors of surgical complications or hospitalization >10 days (no deaths reported).

Materials and Methods

We retrospectively searched all patients with XGP treated at our institution from 2005 to 2019, with 57 patients enrolled. Clinical data were retrieved by a single reader, computed tomographic (CT) examinations by two radiologists, and histopathological specimens by an experienced pathologist.

Results

The patients' mean age was 44.3 ± 16.2 years and 41 (71.9%) were female. The most common symptoms were flank/lumbar pain (89.5%), fever (43.9%), and recurrent urinary tract infection (43.9%). The mean time until the presumptive diagnosis was 365.1 days and the median hospitalization period was 11 days. Blood tests showed anemia (78.9%), leukocytosis (43.6%) with left shift (21.6%). Urinalysis showed hematuria (75.6%), bacteriuria (40.9%), and leukocytes (93.2%). Urine cultures showed Escherichia coli in 14.8%, Proteus mirabilis in 7.4%, while 59.3% were negative. Of 40 patients with CT examinations, 38 (95%) presented with hydronephrosis and perinephric inflammatory changes (PIC) and 22 (55%) with Bear Paw sign. PIC was the only independent predictor at multivariate analysis for surgical complications. For prolonged hospitalization, fever and PIC were independent predictors at univariate, but only fever at multivariate analysis.

Conclusions

XGP is a worrisome condition, with unclear pathophysiological mechanisms. Fever and PIC at CT examinations were predictors of poor outcomes.