The congenital mesoblastic nephroma: a case report of prenatal diagnosis.

The congenital mesoblastic nephroma is a very rare benign congenital renal tumor. It is the most common renal tumor before the age of 6 months (50%) and it constitutes only 5% of renal tumors before 15 years. The authors report a case of prenatal diagnosis of congenital mesoblastic nephroma revealed by an acute polyhydramnios at 33 weeks of pregnancy. After a preterm labor, the patient delivered at 35 weeks. The newborn underwent a radical nephrectomy. No recurrence was noticed at 10 months. This case of prenatal diagnosis is compared to the 12 cases previously reported. The prognosis of CMN depends on histologic findings, but also on the severity of prematurity induced by the polyhydramnios. The main treatment of this pathology if diagnosed during pregnancy remains the prevention of preterm labor, and after birth the removal of the kidney.