[Congenital mesoblastic nephroma with multiple cysts].

Mesoblastic nephroma is a rare, benign congenital disease with a clinical presentation similar to that of Wilms tumour. It was described for the first time by BOLANDE in 1967. The authors report the case of a 6-month-old infant admitted for investigation of an abdominal mass. The radiological assessment (ultrasonography. CT) concluded on a right intrarenal retroperitoneal tumour occupying almost all of the abdominal cavity, predominantly cystic suggesting a diagnosis of non-metastatic Wilms tumour. Radical ureteronephrectomy was performed. The outcome was favourable with a follow-up of 2 years. Histological examination corrected the diagnosis to mesoblastic nephroma by showing a fibrous tumour composed of spindle cells resembling muscle cells, associated with intracystic haemorrhage. The authors emphasize the clinical and radiological features of this tumour, its treatment (exclusively surgical) and its good prognosis (98% survival).