Photo-therapy With a Topical Retinoid Versus Photo-therapy Alone for Actinic Keratoses

Inclusion Criteria * Adults aged 18-80 years old * Subjects with AK lesions who will receive PDT * Subjects with AK lesions in two areas other than face and scalp each with a surface area of 10cm2 or greater and at least 3 clinically diagnosed non-hypertrophic AK lesions in each * Subjects in good health * Subjects with willingness and the ability to understand and provide informed consent Exclusion Criteria * Subjects who are pregnant or lactating * Subjects with a history of cutaneous photosensitivity or porphyria, hypersensitivity to porphyrins, or photodermatosis * Subjects with use of photosensitizing drugs within 1 week of study start * Subjects with use of topical medications such as corticosteroids, alpha-hydroxyacids or retinoids 2 weeks before study entry * Subjects who received previous treatment of target AKs within 4 weeks * Subjects who are unable to understand the protocol or give informed consent