Hyperreninemia and congenital mesoblastic nephroma: case report and review of the literature.

A 32-week estimated gestational age female infant had elevated systolic blood pressure at birth and a palpable left abdominal mass. Radiologic evaluation revealed a left upper pole renal mass. The renin level was significantly elevated. Left nephrectomy confirmed a diagnosis of congenital mesoblastic nephroma. The postoperative renin level normalized along with the blood pressure. Histologic analysis identified renin production from either the mesoblastic nephroma or secondarily from compression or ischemia. Mesoblastic nephroma should be considered as part of the differential diagnosis for hypertension in the young. The renin concentration and a renal ultrasound scan should be obtained as part of the evaluation.