Congenital mesoblastic nephroma: a rare pediatric neoplasm.

Congenital mesoblastic nephroma is a stromal neoplasm of infancy. It has been referred to as mesenchymal, cystic or leiomyomatous hamartoma. These tumors are centered around the hilus of the kidney. Mesoblastic nephromas need to be distinguished from other pediatric renal neoplasms as these lesions are treated by complete surgical excision without chemotherapy unless gross residual tumor remains. Here, we describe the gross and microscopic features of mesoblastic nephroma in a twenty-day old infant.