The purpose of this study is to to compare photodynamic therapy (PDT) versus the combination of Jessner's solution and 35% trichloroacetic acid (TCA) chemical peels for the treatment of actinic keratoses on upper extremities.

This is a randomized clinical trial. Approximately 60 participants with actinic keratoses on both upper arms will be randomized to have one arm receive photodynamic therapy, while the contralateral arm receives Jessner's solution followed immediately by 35% TCA. AKs will be counted before treatment and 2-8 weeks after treatment. This study is a pilot study designed to determine the feasibility of this procedure.

Subjects currently living in the Chicago metropolitan area and meet inclusion/exclusion criteria will be considered for enrollment.

Inclusion Criteria:

1. >18 years of age
2. Interested in receiving treatment for actinic keratoses on the bilateral upper arms
3. In good general health as assessed by the investigator
4. Participants must have the ability to understand and the willingness to sign a written informed consent prior to registration on study

Exclusion Criteria:

1. Patient pregnant or nursing
2. Patient with extensive concurrent skin conditions (such as eczema, psoriasis, etc) on upper extremities that would interfere with treatment as determined by the treating physician
3. Subject unwilling to sign an IRB approved consent form
4. Participants who are unable to communicate or cooperate with the investigator due to language problems, poor mental development, or impaired cerebral function are not eligible