# Xanthogranulomatous pyelonephritis in a 47-day-old male infant: a case report

## TL;DR

A rare kidney infection in a 47-day-old infant was successfully treated with antibiotics, avoiding surgery.

## Contribution

Demonstrates successful antibiotic treatment of focal xanthogranulomatous pyelonephritis in infants.

## Key findings

- XGP was diagnosed in a febrile infant with a renal mass using histopathology and metagenomic sequencing.
- Targeted antibiotic therapy led to regression of the lesion and normalization of tumor markers.
- The case supports non-surgical management of focal XGP in infants.

## Abstract

Xanthogranulomatous pyelonephritis (XGP), a rare granulomatous renal disease linked to bacterial infection (e.g., Escherichia coli), presents challenges in pediatric diagnosis, especially in infants, due to overlap with neoplastic renal masses like Wilms tumor.

A 47-day-old male infant with fever, elevated inflammatory markers (WBC 13.94 × 109/L, CRP 110.43 mg/L), and urinary leukocytes/hematuria showed a left renal mass (1.7 × 1.8 × 2.1 cm) on imaging. Biopsy revealed histiocytic-neutrophilic infiltration with focal necrosis, and metagenomic sequencing identified dominant E. coli. Antibiotic therapy (cefoperazone-sulbactam followed by cefdinir) induced regression (1.1 × 0.8 × 1.1 cm at 2 weeks). Elevated AFP (888.27 ng/ml) normalized, excluding malignancy.

This case highlights XGP as a critical differential diagnosis for febrile infants with renal masses. Integration of histopathology, metagenomic sequencing, and prolonged follow-up confirms that focal XGP can be managed successfully with targeted antibiotics, avoiding nephrectomy.