The x-ray shows a perfectly normal leg. That, House says, is the problem. He takes a few pills, and Wilson just goes "wha-what...?" like it never occurred to him that House would find a way to get his pain meds. His shock and disbelief are pretty funny, though. House adds that their "dwarf" has normal growth plates. This, Cuddy points out, is impossible. Wilson asks House how many pills he's taken. "Not as many as I'm gonna take. Forgotten how delicious they were," House smiles. He tells Wilson and Cuddy to forget his vices and concentrate on his virtues -- namely, that he's brilliant. The only way a dwarf can have normal growth plates is if she's not a dwarf. Everyone assumed that she was one because of her mother, and House says that there's no test for CHH. Although you'd think someone would have, like, taken an x-ray or something somewhere along the line and noticed the growth-plate thing, wouldn't you? Maddy should have taken her kid to St. Sebastian's. So now they have one more symptom to add to Abigail's list: stunted growth. That means she has a long-term pituitary gland problem, the pituitary gland being the thing that secretes the growth hormone. Cuddy and Wilson, of course, are totally lost as to what this could be, so House helps them along. It's not cancer, and it's not an autoimmune thing; it's both! Cameron and Wilson will have to share the trophy. Although it should really go to Chase, who figured out what this was a long time ago. Not that anyone cares or will acknowledge this. And if Chase tries to take credit for it, he'll probably get punched in the face again. House explains that Abigail has Langerhans cell histiocytosis. The autoimmune component to the disease improved when they treated her for Still's disease. But the cancer part didn't respond to that, so she got worse again. Cuddy says that they dismissed Langerhans because Abigail didn't have any neurological symptoms. "It's not your fault. The only neurological symptom was her height. Who could've noticed?" House rubs it in. Ah, but he is brilliant. They should play the music that used to play when Popeye ate spinach whenever House takes his pills. Opiates give House super-diagnosis powers!
House explains Langerhans to Abigail and Maddy. He shows them an image of Abigail's brain, pointing out her pituitary gland and the tumor that's been crushing it. Uh, yeah...way to catch that tumor in those CT scans and MRIs of Abigial's head, guys. Maddy can't believe what she's hearing: her daughter isn't a dwarf after all. Abigail asks about her mother, and House says that she is the "real deal." A small victory for Maddy. Abigail's ear infections caused a cascade of the same cells that created that tumor. Those cells attacked her internal organs, causing all her problems. Now, all they have to do is nuke the cells with chemotherapy and then surgically remove the tumor. Mom asks what will happen then, and House provides a visual demonstration. His oxycodone pill represents growth hormone and he kneels down to represent short Abigail. He dry-swallows the pill and stands upright to represent a taller Abigail. She will never be a giant, but she'll definitely be more average height than her mother. Abigail thinks, and then asks what happens if she doesn't take the growth hormone. "Your body needs growth hormone for lots of things. Like, to grow," House says, not having any of this. Abigail says that she doesn't want to grow: "I like who I am now." Her mother smiles proudly. House asks Abigail if she really wants to go through life not being able to reach things and being at eye-level with everyone else's ass. Growth hormone, House says, is Abigail's "ticket out of the freak show." Yeah, call her mother a freak. That'll win Abigail over.