An overgrowth of skin layers resulting from extended exposure to the sun WordNet 3.0 & Open English WordNet

Actinic keratosis, sometimes called solar keratosis or senile keratosis, is a pre-cancerous area of thick, scaly, or crusty skin. Wikipedia

A skin condition Wikipedia Disambiguation

Human disease Wikidata

A potentially precancerous skin lesion, typically on the upper portion of the head, characterized by discolored, thickened or scaly growths of keratin and caused by repeated exposure to ultraviolet light, such as from sunlight or tanning beds. Wiktionary

Skin lesion characterized by discolored, thickened growths of keratin. Wiktionary (translation)