In the office, Louis brings Dr. Lee up to speed on the history of his condition, and his theory that it dates back to Vietnam. "This is way beyond athlete's foot or severely dry skin," Dr. Lee says as she inspects his skin. "I've seen something like this in textbooks, but never in person." Taking into account the safest way to proceed — considering Louis's age and the rarity of his condition — Dr. Lee performs what's called a punch test , where she biopsies the top layer of dead skin, plus the fat layer just below the surface, and sends that sample to the lab to find out what's really going on.