Xanthogranulomatous pyelonephritis: the case of a perplexing kidney.

To cite: Said Conti V, Azzopardi C, Fearne C, et al. BMJ Case Rep Published online: [please include Day Month Year] doi:10.1136/ bcr-2014-206172 DESCRIPTION Case report A previously healthy 2-year-old girl presented with turbid urine and pallor. She was otherwise asymptomatic and afebrile. Clinical examination revealed a large ballotable right-sided abdominal mass. Ultrasound revealed an enlarged right kidney with loss of the normal renal architecture, which was replaced with multiple hypoechoic nodules. A number of renal calculi were observed with typical acoustic shadowing (figure 1). A contrastenhanced CT scan demonstrated the diagnostic ‘bear’s paw’ sign, multiple calculi, retroperitoneal lymphadenopathy and a small right psoas abscess (figure 2). A dimercaptosuccinic acid (DMSA) scan demonstrated a non-functioning kidney (figure 3). Urine cultures tested positive for Proteus mirabilis. The patient initially underwent a percutaneous nephrostomy and received antibiotics. Subsequently, a radical nephrectomy was performed. Extensive inflammatory adhesions to the inferior vena cava, liver and surrounding tissues were found. She recovered fully postoperatively and remains well.