A case of xanthogranulomatous pyelonephritis mimicking Wilms tumor.

Xanthogranulomatous pyelonephritis (XGPN) is a very rare, unusual variant of pyelonephritis characterized by destruction of renal parenchyma. It usually occurs in adults with a history of recurrent urinary tract infections. The condition is rare in children and the disease can imitate renal tumors. Here, we describe a 12-year-old boy who presented with abdominal pain. He did not have any history of urinary tract infection. Computed tomography and magnetic resonance imaging showed a cystic lesion in the left upper kidney. The patient underwent radical nephrectomy with a provisional diagnosis of Wilms tumor however histopathological examination of specimen revealed XGPN. Xanthogranulomatous pyelonephritis should be kept in mind in the differential diagnosis of renal lesions in childhood, during surgery if any suspicion from the diagnosis, a frozen biopsy should have been taken.