The Effect of Topical Imipramine on Photodynamic Therapy-Mediated Immunosuppression on Forearms or Face on US Veterans

The purpose of this study is to test the use of topical imipramine in combination with topical photodynamic therapy's (PDT) effect on the effectiveness and pain immunosuppression following treatment. PDT is a commonly used treatment in dermatology for patients who have many pre-cancers (actinic keratosis or "AK") on their skin. These are both FDA-approved medications, but this study is evaluating their use in combination, which has not been evaluated in the past. The investigators have been doing studies using mice that suggest imipramine might reduce immune system suppression by PDT thus allowing it to work better. Subjects whose provider has decided that they may benefit from PDT to treat their skin due to many AK precancerous lesions will be recruited for this study. Please note that the PDT itself is not experimental, only the imipramine treatment to the skin. There is a separate informed consent for the PDT.