Xanthogranulomatous pyelonephritis in a paediatric cohort (1963–2016): Outcomes from a large single-center series

Summary Background Xanthogranulomatous pyelonephritis (XGP) is an uncommon chronic destructive granulomatous inflammation of the kidney. It was first described in 1916, and is thought to affect 6/1000 cases of pyelonephritis. Its manifestations are varied, and with a limited number of cases in the literature, the optimal diagnosis and management of XGP in the paediatric cohort is still unknown. Material and methods The medical records of children who were diagnosed and treated for XGP at the current unit during the period 1963–2016, inclusive, were retrospectively reviewed. Information pertaining to each patient was recorded, including: demographic data, past medical history, clinical and biochemical characteristics, diagnostic procedures, treatment methods, histopathologic diagnosis of the removed specimen, and outcome. Results A total of 66 children with a median age of 4.84 years (range 1.1–14.81), with an M:F ratio 1.35:1 underwent nephrectomy for XGP and had a median follow-up of 7.19 years (range 0.11–17.45). The most common presentations were systemic illness (62.1%), pain (60.6%), urinary tract infections (54.5%) and an abdominal mass (39.4%); pyrexia was present in 53%. Biochemical abnormalities included anaemia (86.3%), thrombocytosis (80.3%) and hypomagnesemia (65.1%). There was an 83.3% concordance between intraoperative cultures and positive mid-stream urines. Index kidneys were significantly larger than the contralateral side (mean 1.32 cm; P  = 0.002). Staging of XGP demonstrated extension beyond the kidney in 79% of kidneys. Computed tomography (CT) was performed in 11 cases (Summary figure). Dimercaptosuccinic acid (DMSA) scan showed 0–10% function in 90.47% of cases. Surgical procedures included nephrectomy ( n  = 63) and partial nephrectomy ( n  = 3). Perioperative complications included colonic resections ( n  = 5) and abscess formation in 18%. Conclusions This is the largest series to date of XGP in a paediatric cohort. XGP should be included in the differential diagnosis of all children presenting with perirenal or psoas abscesses, renal masses and/or non-functioning kidneys with/or without associated urolithiasis. Clinical awareness and a high index of suspicion is required to achieve the correct pre-operative diagnosis and appropriate management. Download high-res image (369KB) Download full-size image Summary Figure . Pathognomonic CT feature of xanthogranulomatous pyelonephritis: ‘bear-paw’ sign.