Actinic keratosis is a premalignant condition of thick, scaly, or crusty patches of skin. It is more common in fair-skinned people and it is associated with those who are frequently exposed to the sun, as it is usually accompanied by solar damage. They are considered as potentially pre-cancerous, since some of them progress to squamous cell carcinoma, so treatment is recommended. Untreated lesions have up to 20% risk of progression to squamous cell carcinoma.
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