An 18-year old woman went to the doctor for abdominal pain and a 40-pound weight loss. When the doctor performed a CT scan, they found a mass which turned out to be a 10-pound hairball!
Doctors found a mass there, and when they used a small camera, found that the hairball was taking up nearly her entire stomach.
The patient said that she has a habit of eating her own hair, a condition called trichophagia.
Doctors tried to use small incisions to remove the mass, but then had to go to traditional surgery to make sure the entire hairball was removed.
Link (with video) - via BelchSpeak
As for the disorder... One of my friend's nieces had that same problem whilst in high school. One day I saw the girl's school pic hanging on my friend's kitchen fridge. In the photo she was wearing some sort of odd head scarf. Not knowing her problem, I stick my foot in my mouth (again), and say "Hey Josh, what's with that wacky do-rag on your niece?" I then got the whole story about how she likes to eat her hair and there was a big bald spot when school pic time came around. I had never heard of something so wacky, but considering some teenager chicks hack their bodies up with razor blades, this is almost tame. The good news is I think they got the kid a first class shrink who straightened her out. No do-rag over a bald spot in any event...