Ichthyosis 2008-04-02T03:41:00Z An abnormality of the skin characterized the presence of excessive amounts of dry surface scales on the skin resulting from an abnormality of keratinization. Ichthyotic skin UMLS:C0020757 Ichthyosiform abnormality of the skin HP:0007547 HP:0008064 MEDDRA:10021198 Hypertrophic ichthyosis The ichthyoses are a group of skin diseases characterized by drying and scaling of skin with the accumulation of thick scales and cracks that may be painful or bleed. The abnormality in ichthyosis lies in am imbalance in the normal lifecycle of skin in which growth is matched with dying and shedding of skin cells. In ichthyosis, skin cells reproduce at a rate faster than dead skin cells can be shed or reproduce at a normal rate with a reduction in the rate of shedding. Either abnormality leads to a build up of dry and scaly skin. Note that this term refers to the morphological abnormality of the skin and not the disorder. Ichthyosis can have a congenital onset or be acuqired, e.g., paraneoplastic ichthyosis. HP:0000955 Epidermal thickening