Congenital mesoblastic nephroma is the most common neonatal kidney tumor. It is generally benign in nature and is mostly curative by surgical excision. Congenital mesoblastic nephroma has been mistaken for Wilms tumor and subsequently overtreated. Therefore, awareness of congenital mesoblastic nephroma will aid in giving proper therapy.
We report a case of congenital mesoblastic nephroma diagnosed prenatally by sonography. A 28 year old woman at 35+5 weeks of gestation was referred to our hospital for fetal abdominal mass. An ultrasongraphy revealed a huge, well-encapsulated mass arising from the right kidney. After birth, right nephrectomy was performed. It was diagnosed as mesoblastic nephroma by histologic examination.