In last week’s episode, a patient arrived at Seattle Grace Mercy West with a condition none of the doctors had seen before and would likely never see again. Jerry Adams had “Tree Man” disease, which is indeed a real affliction. As the docs explained, it happens when Human Papillomavirus (better known as HPV) causes warts to grow on the body. That’s not uncommon, but when the patient has a deficient immune system, the body is unable to control the warts, causing “cutaneous horns.” As Dr. Anthony Gaspari of the University of Maryland states, a low immune system causes HPV to “hijack the cellular machinery of the skin cells.” But, if there is a bright side, it’s that there are no nerves in the horns, meaning they don’t cause their bearer any pain. Still, the emotional pain these patients must endure makes us hope that researchers will find a definitive cure soon.