ACTINIC KERATOSES - CAUSES
People who are fair-skinned an who have spent a good deal of time outdoors are the most at risk for actinic keratoses, though they can also develop in people with darker skin types.  In addition, people who work outdoors or who have exposed their skin to indoor tanning are also at risk.  With time and long-term sun exposure, the skin takes on a wrinkled, sallow, mottled appearance, and, eventually, precancerous lesions develop.  Other populations at risk include people with suppressed immune systems, such as transplant patients, as well as patients with psoriasis or eczema who have been treated with phototherapy.  Such individuals should be screened annually for evidence of actinic damage, and they should follow sun safety measures at all times.

The most common areas for actinic keratoses are those that have received chronic sun exposure, including the face, particularly the cheeks and nose, scalp, back of the neck, upper chest, and the backs of the hands and forearms.  In addition, men are more likely than women to develop actinic keratoses on the tops of the ears, because the longer hairstyles of women tend to protect those areas.