Mesoblastic nephroma

Congenital mesoblastic nephroma is 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.

Differential diagnosis
A common differential diagnosis includes the following tumors:
 * Mesoblastic nephroma (congenital): from birth to 1 year
 * Rhabdoid tumor: from 1 to 2 years of age
 * Clear cell sarcoma of kidney: from 2 to 3 years of age.
 * Wilm's tumor: over 3 years of age.

The age breakdown is far from exact, but provides a useful age range and approximate order. Wilm's is most common, accounting for 80-85% of all pediatric kidney tumors. Congenital mesoblastic nephroma accounts for about 10-15%; rhabdoid and CCSK split the remained 5-10%.