Actinic keratosis (AK), also known as solar keratosis, is a small crusty or scaly bump or horn that arises on or beneath the skin surface and is the result of prolonged exposure to sunlight. Early on, it may disappear only to reappear later. These AK lesions are most likely to appear on the face, lips, ears, scalp, neck, backs of the hands and forearms, shoulders and back – the parts of the body most often exposed to sunshine. By far the most common precursors of skin cancer, AK lesions are often recognized by touch rather than sight, occasionally itching or producing a pricking or tender sensation. They can become inflamed with surrounding redness and in rare instances, they can bleed. It is important to have a physician check the status of any lesion present on the skin. PDT (Photodynamic therapy) has been used by physicians to treat actinic keratosis which involves using either Blue light or IPL ( Intense pulse light) in combination with ALA (Aminolevulanic Acid) solution.