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

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.