Actinic keratosis (AKs) is a pre-cancerous growth that presents as a rough, scaly patch on the skin caused by years of sun exposure. It is most common on the face, lips, ears, back of hands, forearms, scalp, and neck. Blue light photodynamic therapy is a minimally invasive treatment that is approved by insurances to treat AKs on the face and scalp. A series of two blue light (Levulan Kerastick) treatments is recommended in the fall or winter.