The surgeons prepare to change Matty's life as he knows it without forewarning him. Since we aren't even halfway into the episode yet and Wilson, the Angel Of Death, is lurking around the operating room, I have a very bad feeling about this.
Who watches curling on television? House does, although he's understandably fallen asleep from boredom when his phone rings and wakes him up. It's Wilson, who says they didn't remove Matty's mitral valve during the operation after all; they did a biopsy on the heart growth first and found out that it wasn't infectious tissue. I still don't understand why no one on this show can properly identify a mass. They are always thinking it's one thing when it's actually something else. How can they have the technology and ability and know-how to operate on a fetus while it's inside the womb and still not know if a spot on an MRI is cancer or pus? "Oh, god," House says. He's not horrified at the thought of almost ruining Matty's life for no reason, though: he's just realized that Hector got into his Vicodin and is lying on the floor looking dead. I guess it's a good thing Wilson didn't take that dog in after all, since we all know he would have left Hector there to die. House pokes the dog with his cane and is clearly disappointed to find him alive but strung out on Vicodin. My friends' dog ate part of a Sudafed once and was in doggy ICU for days. Hector must have quite a tolerance there.
House returns to work and asks for a differential diagnosis on fibrous tissue growth in the heart. Cameron comes up with an autoimmune disorder, which pleases Wilson greatly, as it would mean Matty's bone marrow was healthy and donatable. You know who probably won't be as pleased? Matty. But no one cares about him. House starts giving orders to test the most likely autoimmune disorders until Foreman interrupts, saying he doesn't think they should rule out an infection just yet. House doesn't want to deal with that, because an autoimmune disorder would mean a good outcome for Nick. Foreman finds it hard to believe that the family has one son with cancer and another with an autoimmune disorder. House says that "it sucks for them" is not a good argument. Foreman wants to check out a close match he found in the bone marrow registry. It's not an exact match like Matty is, but Foreman thinks it'll be close enough. House doesn't want to risk giving precious Nick graft-versus-host disease, and he overrules Foreman and tells the Cottages to go look for an autoimmune disease.