According to the head of the Laboratory for Investigative Dermatology at Rockefeller University, James Krueger, it is sometimes said that dermatologists do one of two things: Faced with a skin disease that's too dry, they try to wet it; if the disease is too wet, they try to dry it (although it isn't usually dermatologists who say this).  According to Krueger, "A hairdryer or a sponge doesn't make a very good therapeutic. We need to do better. We need to be more specific."

Looking specifically at psoriasis and atopic eczema (the two most common forms of inflammatory skin disease), researchers have been able to distinguish between them using genetic and immunological signatures.

http://www.sciencedaily.com/releases/2009/12/091231150117.htm