Isolated hemihyperplasia is a rare overgrowth syndrome characterized by an asymmetric regional body overgrowth, involving at least one limb, and associated with an increased risk of developing embryonal tumors principally nephroblastoma (see this term) and hepoblastoma. The disease is Orphanet rare-disease nomenclature entry Orphanet_2128 (Hemihypertrophy). Also known as: Hemi 3 syndrome, Hemicorporal hypertrophy, Isolated hemihyperplasia.