Pathology: Renal cell carcinoma, papillary type, Fuhrman grade 2, with extension into the IVC.

Horseshoe kidney is the most common renal fusion anomaly.

Incidence 0.4-1.6 in 10,000 live births, males > females

Associated with an increased risk of Wilms tumor, transitional cell carcinoma, and primary renal carcinoid tumors (62x).