PDT is short for photodynamic therapy. PDT utilizes medication applied topically to the skin combined with controlled application of various wavelengths of light in order to treat various skin conditions. Photodynamic therapy is most commonly used to treat actinic keratosis. Actinic keratosis are pre-skin cancers that develop after years of sun exposure. PDT allows us to perform what is called field therapy. So, rather than simply destroying each individual lesion, the entire area of sun damaged skin can be treated. A delightful side effect of photodynamic therapy is improved cosmetic appearance of the skin. In fact, PDT can also be used in patients without pre-skin cancers to improve the appearance of the skin. It is also commonly used to treat acne in patients who are either unresponsive to traditional therapies or unwilling to take oral medications.