Actinic keratoses are precancerous lesions that if untreated may progress to invasive squamous carcinoma. Clinically they are manifested by a hyperkeratotic (scaling) lesion often on a pink base. The scale is very adherent. When rubbed the lesion is often tender. Actinic keratoses are frequent in areas of maximum sun exposure. Whereas basal cell carcinomas and melanomas occur most frequently on skin areas receiving intermittent severe sun damage, squamous carcinomas occur in areas of the skin receiving maximum lifetime exposure. These areas include the face, scalp in balding individuals, dorsum of the hands, arms and legs, as well as elsewhere if there has been severe sun damage.
Progression to squamous carcinoma is usually slow, extending over many years. While some actinic keratoses can disappear spontaneously, it is generally a good practice to treat these lesions. The use of sunscreens can prevent the development of actinic keratoses, and by inference, squamous carcinomas.
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