A renal tumour which has a multicentric origin -

Wilms tumor Wilms tumor is the most common primary renal tumor of childhood. The usual age for diagnosis is 2-5 years. Approximately 5% to 10% of Wilms tumors involve both kidney, either simultaneously or one after the other. Nephrogenic rests are the precursor lesions of Wilms Tumor. Most children with Wilms tumors present with a large abdominal mass. Less common presentations are hematuria, abdominal pain, intestinal obstruction, and hypertension. "10% of Wilms tumors are either bilateral or multicentric at the time of diagnosis". - Robbin's