Chase wonders if they're looking at something genetic. He points out that Lucy and Jasper's mother might have died from the same thing. Cameron doubts this, saying they didn't find any tumors in Jasper's brain or Lucy's, and that the mom didn't show these symptoms before she died. Chase says that if the symptoms are pubic hair and menstruation, then she did. "That's ridiculous. If menstruation is a symptom of brain cancer, then I should be on chemo right now," Cameron overshares. I guess this explains why she's being so bitchy to Chase, though. "That's ridiculous. You're way too skinny to be menstruating," House responds. He tells them to pull the mother's medical files and look for any similarities, and to be sure to bleed Jasper out so he doesn't have a stroke like his sister. I'm sure Chase would be happy to oblige.
But no, Foreman's the one who gets to bleed Jasper, who angrily requests Cameron instead. Get the hint, Jasper -- she doesn't have feelings for you. Hotter guys than you have been similarly rejected. Foreman ignores Jasper and talks to Deran, who asks if Jasper's recent behavioral problems are because of the testosterone. Foreman says that they probably are. I didn't know testosterone made you an obnoxious asshole, but I can't say that I'm surprised. Lucy starts crying out that her tummy hurts. Jasper tells her to stop being a baby, because testosterone makes you mean to your sister. Lucy starts screaming in pain.
There are cysts all over Lucy's internal organs. The hormones, Foreman explains, are causing the cysts. If she gets one in the wrong place, she'll be dead. Cameron and Chase finish looking through the mom's medical files and find nothing of import. Cameron concludes that they've ruled out environmental and genetic causes, so it must be a pituitary tumor. One of those special ones that siblings coincidentally get at the same time but no one can see on the scans. House thinks it must be environmental, but the Cottages protest that Lucy is out of her environment and getting worse and they haven't found anything in her environment after a night of testing. Cameron decides to take matters into her own hands, just like Chase and Foreman did when they decided to go home and let everyone else do the work. This time, House does not congratulate her gumption, but instead tells her not to. He points out that they have no evidence that it's a brain tumor, and considering that the source is a guy who will do just about anything to his patients with evidence like "he dove into water that was cold," that's pretty big. But Cameron won't be moved unless it's towards Deran with a consent form.