House studies the Whiteboard of Symptoms and fills about half a minute of time.

After the commercial, Foreman and Chase have joined House in the meeting room, where everyone is frustrated at the lack of a diagnosis for Mary's case. House says that they must be missing something, and prods them to focus on what they already know. They say that Mary is twelve, spends a lot of time in the pool and traveling around the country, and...that's it. "Come on!" House barks, but they have nothing.

The meeting resumes outside Mary's room, which is finally a real one and not a space in the hallway surrounded by curtains or down in the morgue. I hope Cuddy kicked Nurse Brenda's ass to get that. House says they're missing something. "What?" Chase asks stupidly. ["Someone has to fill the void Cameron left." -- Wing Chun] House says that if he knew what it was, it obviously wouldn't be missing, and Chase takes a minute to inhale a deep breath or two and calm down before he does something he regrets even more than telling Vogler about the ipecac. House notes that there are a lot of balloons in Mary's room, and asks Foreman who gave them to her. He says that some of Mary's female teammates brought them when they visited. House asks why the male swimmers haven't been around. Mary's "cute" and "nice" and a "kick-ass diver," so shouldn't she have a line of admirers out the door? Foreman says that the youngest guy is sixteen, so, no. House says that could be why, or maybe..."they're avoiding her," Chase finishes. Yes, that just could be it! Surely the only reason people would have for staying away from a quarantined den of meningitis germs is that they have a personal issue with one of the patients trapped therein. House orders Foreman and Chase to re-test Mary's blood cells for fragments.

Although an earlier test showed no fragments, Chase reports that Mary's blood now looks like it was put through a blender. House enters, and they tell him that Mary's rash isn't a rash at all, but bleeding into Mary's skin. She's got a case of thrombotic thrombocytopenic purpura, to be exact. Foreman wonders what could have set it off, as associated estrogen-related causes like menopause are obviously not a reason. "There is one other possible cause," House says gravely. Actually, the same internet search that helped me correctly spell TTP also said that it is often idiopathic, meaning that there is no known cause, and that it can be detected quite easily in routine bloodwork, so it probably should have been caught much earlier, although I guess the state of epidemic chaos can excuse that. Plus, this way gives us more drama, so we'll go with it. Realizing what House is talking about, Chase says "oh, God," and Foreman shakes his head.