Laser and Microdermabrasion Before Photodynamic Therapy for Actinic Keratoses in Field-cancerized Skin

Inclusion Criteria: * Patients with two skin areas of at least 50 cm2 with a minimum of 5 actinic keratoses (AKs) grade I-III, chronically sun damaged "field" changes in one of the following anatomical regions: face, scalp, upper chest. * Patients who have given written informed consent and are believed to be capable of following the study protocol. * Fertile women must have a negative pregnancy test (urine-hCG) at the time of inclusion and use anti-contraception (oral contraceptives, intrauterine device, gestagen depot injection, subdermal implantation, vaginal ring, transdermal depot bandage or sterilisation) during the study. Exclusion Criteria: * Patients that have within the last month received local treatment in the test areas. * Pregnant or nursing patients. * Patients with porphyria * Patients with skin cancer, keratoacanthoma, or other infiltrating tumors within the test areas. * Patients with a tendency to develop hypertrophic scars or keloids. * Patients with a known allergy to Metvix cream * Patients that are believe unlikely to follow the study protocol.