squamous hyperplasia actinic keratosis Discrete, flat or elevated, verrucous, keratotic lesions. Epidermal changes are characterized by acanthosis, parakeratosis, and dyskeratoses. Dysplastic change is present and the keratinocytes vary in size and shape. Associated with UV exposure in humans. Not defined in mice to date. George Gkoutos MPATH:151 mouse_pathology.ontology potentially cancerous lesions