[Bilateral Wilm's tumor in the fetus]

The author reports a case of Wilms' tumor in a stillborn fetus and emphasizes the extreme rarity of this diagnosis in fetus and at birth despite monitoring pregnancy frequent sonography. There is no report of in utero ultrasound diagnosis of Wilms' tumor. Wilms' tumor develops from nephrogenic blastema rests which usually disappear after 34 weeks of gestation. Pediatric autopsies show that blastematous foci may persist after birth without necessarily forming nephroblastomas. Their frequency is one hundred times higher than that of nephroblastomas although they are often associated. Wilms' tumors are hereditary and more frequent in patients with congenital malformations related to genetic disorders. Because of therapeutic progress the diagnosis should be made very early particularly in high risk patients using sonography during pregnancy despite problems of interpretation and soon after birth.