Addie finally realizes that she's in the MRI of DOOOM! and it is aptly named. She starts groaning and complaining of head pain. Foreman says that her MRI is clean of tumors and abscesses. Addie's groans turn into screams, and Cameron and Foreman ever so slowly make their way into the MRI room to tend to her. And there, they see a pool of blood leaking out of what appears to be a giant hole in the top of Addie's skull. Like, I think I'm looking at brain matter there. TMI, Addie. Also, how the hell did they miss that on the MRI?
When we get back from commercial, the Cottages are cleaning up the mess of Addie's head while House films it all with a video camera for some reason. It's like he's making his own amateur porn as he swings the camera around, shooting an annoyed Cameron's face after she says that what is coming out of the hole in Addie's head isn't pus and therefore is not the result of an infection. But House still thinks they're looking at an infection. I'm still not sure if we're looking at brain or at scalp that looks a lot like brain. House says this wound means that either Addie has a leprechaun in her colon that's forcing bacteria that's supposed to be expelled out of her back into her, or she has CFH deficiency. Never before has someone been so cheery about a fatal illness. Fortunately, Addie is not awake while House sing-songs that he's saving her life, albeit by diagnosing her with a fatal disease. Chase has another theory, but House dismisses it because it doesn't fit all of Addie's symptoms. Unlike his infection theory, which hasn't fit any symptoms at all. Chase wants to treat Addie for an autoimmune disorder, and they'll have to give her steroids RIGHT NOW for her to have any chance of surviving. House says that if it isn't an autoimmune disorder, the steroids will kill her. This little medical Mexican stand-off seems to happen, like, every single episode. It's getting a little tiresome, guys. ["Seriously, dude. I don't even watch this show, and even I was like, 'Again?'" -- Miss Alli] House reminds the group that treating someone for the wrong thing can kill her, citing Foreman as an example of this. Then he tells Chase that if he really thinks it's autoimmune, then he can go ahead and give Addie steroids. If he's wrong and she dies, he can just quit like Foreman did. He instructs Cameron to be sure to stand over Addie with defibrillator paddles while Chase administers the steroids, because if Chase is wrong, her heart will need them immediately. He says that they can have fun explaining that to Addie's parents. Well, at least someone will be explaining something to those poor people.