The outcome of prenatally diagnosed renal tumors

A retrospective study at 20 institutions identified 28 children who had a renal tumor diagnosed prenatally. In all but 2 cases, the tumor was diagnosed at routine ultrasonography (US) in the third trimester. The median fetal age at the time of diagnosis was 30 weeks gestation, A majority of tumors appeared heterogeneous on US. Nearly two thirds arose from the right kidney. Cystic components were noted in 7 cases, increased vascularity in 6, and tumor calcifications in 3. None of these features distinguished between congenital mesoblastic nephroma (CMN), present in 26 cases, and Wilms tumor (WT), found in 2 cases. One or more complications developed in 20 cases, in 71% of them during the perinatal period. Polyhydramnios complicated 11 pregnancies; it correlated significantly with both preterm labor and prematurity. Nonimmune fetal hydrops was recognized in 2 cases and acute fetal distress requiring emergency cesarean section in 7. The 27 live-born infants had a median gestational age of 35 weeks. Nearly half of the infants were born before 34 weeks gestation. Complications at birth included hemodynamic instability in 3 infants, 2 of whom had emergency surgery; respiratory distress syndrome requiring mechanical ventilation in 8; and hypertension in 6. Approximately one fourth of infants had surgical complications, including 1 instance of tumor rupture and 1 of intraoperative bleeding. There was a single postoperative death. All the live-born infants had complete resection of the tumor a median of 1 week after birth. Surgical complications occurred in 26% of cases and 1 infant died postoperatively. After a median follow up of 42 months, 26 of the 27 surviving children were in complete remission. Despite the high risk of perinatal complications when a fetus is found to have a renal tumor, the oncologic outcome is, in general, excellent. Delivery at a pediatric tertiary care center is recommended.