congenital mesoblastic nephroma
(kun-JEH-nih-tul MEH-zoh-BLAS-tik neh-FROH-muh)
A type of kidney tumor that is usually found before birth by ultrasound or within the first 3 months of life. It contains fibroblastic cells (connective tissue cells), and may spread to the other kidney or to nearby tissue. Congenital mesoblastic nephroma is more common in males.