Definition: A small rough thickened spot that appears on skin that has been chronically exposed to the sun. The lesion is considered precancerous because it can develop over years into a skin cancer called squamous cell carcinoma. Actinic keratoses occur most frequently in fair-skinned people. Common locations are the face, scalp, back of the neck, upper chest, forearm and back of the hand.
Pronunciation: Ack-tin-ick Kare-uh-toh-siss
