Harlequin ichthyosis (Orphanet_457) (HI) is the most severe variant of autosomal recessive congenital ichthyosis (ARCI; see this term). It is characterized at birth by the presence of large, thick, plate-like scales over the whole body associated with severe ectropion, eclabium, and flattened ears, that later develops into a severe scaling erythroderma. Also known as: HI, Ichthyosis congenita, harlequin type, Ichthyosis fetalis, Harlequin type.