Definition of Actinic keratosis:

Actinic keratosis is a precancerous skin growth usually caused by sun exposure.

Causes, incidence, and risk factors:

Actinic keratosis occurs most commonly in fair skin, especially in the elderly and in young individuals with light complexions. The growths occur in sun-exposed skin areas. The growths begin as flat, scaly areas that later develop a hard wart-like surface.

They are classified as precancerous growths. If left untreated, approximately 1% of actinic keratoses develop into squamous cell carcinoma.