[Retroperitoneal fibrosis in children].

A 13 year-old boy was hospitalized because of persisted fever had pallor for three months. Abdominal ultrasound, intravenous pyelogram, and abdominal computerized axial tomography scan disclosed a space occupying lesion located postero-superior to the bladder. Biopsies of the above lesion disclosed retroperitoneal fibrosis. Retroperitoneal fibrosis in children is very rare and has a wide variety of presentations and associated diseases. Treatment relief of obstruction when necessary.