Hyperkeratosis SNOMEDCT_US:26996000 Epidermal hyperkeratosis SNOMEDCT_US:399955009 HP:0000962 HP:0007543 HP:0007523 UMLS:C0870082 MEDDRA:10020649 Hyperkeratosis is a histopathological term defining a thickened stratum corneum and may be present in many different skin conditions, with many possible overlaps. Hyperkeratosis refers to the increased thickness of the stratum corneum, the outer layer of the skin. Hyperkeratosis is subclassified as orthokeratotic or parakeratotic. Orthokeratotic hyperkeratosis refers to the thickening of the keratin layer with preserved keratinocyte maturation, while parakeratotic hyperkeratosis shows retained nuclei as a sign of delayed maturation of keratinocytes. SNOMEDCT_US:396228006 Epidermal thickening