“Fritz Fleischer's epidermis —plagued by psoriasis in childhood, then by sun damage in old age — ” develops actinic keratoses. With these words of his alter ego, John Updike (1932-2009) summarizes the consequences of the treatment for his almost lifelong psoriasis.1 Because his old dermatologist had died, Fleischer sought help from a young dermatologist “who gave the impression that all of the things that exist . . . the one that interested him least was human skin. ” He explained to Fleischer in detail the new technology of photodynamic therapy to “flush out precancerous cells. Before they turn cancerous. ”