 Hemihyperplasia is seen in several congenital syndromes including Beckwith-Wiedemann syndrome and Russell-Silver syndrome.Hemihyperplasia is a congenital overgrowth disorder, and the asymmetry can range from mild to severe.Establishing a diagnosis is important because hemihyperplasia is associated with an increased risk for embryonal tumors, mainly Wilms tumor and hepatoblastoma.