[Xanthogranulomatous pyelonephritis with pyonephrosis in a 4-year-old child].

Xanthogranulomatous pyelonephritis is a rare form of chronic pyelonephritis observed in only a few cases in children. Symptoms are mild, which explains the delay in diagnosis. Diagnosis is based on histology but can be suspected on CT. The treatment is medical and often surgical, with an uncertain renal prognosis. It is therefore imperative to diagnose early. We report the case of a 4-year-old child who presented with xanthogranulomatous pyelonephritis caused by Pseudomonas aeruginosa, which evolved into pyonephrosis, due to inadequate antibiotic therapy. This highlights the importance of understanding this disease and not treating urinary tract infections blindly.