Rhabdoid tumor: an aggressive renal medullary tumor of childhood.

We present a case of a renal rhabdoid tumor in a 2-month-old girl. Rhabdoid tumors are rare primary renal tumors in children, but they have characteristic features--medullary sinus invasion and subcapsular fluid collections--which enable a specific diagnosis. The classic imaging characteristics of this tumor compared to other more common primary pediatric renal tumors will be reviewed.