A recurring line from the TV series House, M.D., which I choose to interpret as a brilliant metafictional comment on the show itself.

Dr. Foreman: You stash your drugs in a lupus textbook?
Dr. House: It's never lupus.
-- Finding Judas (season 3, episode 9)

House is a deliberately formulaic program. It draws its inspiration from Sherlock Holmes (House = Holmes, get it? or did you think that House's street address is a coincidence? and that his best friend only just happens to be called Wilson?).

Like Holmes, House notices minute, easily-overlooked details, and uses them to assemble evidence for outrageously bizarre medical cases. If a patient presents with all the classic symptoms of diabetes or AIDS or lung cancer, then House declares that she can't possibly be afflicted with that disease. She must have something more obscure, and House is going to figure out what it is.

The reason viewers tend not to notice the predictability of House, M.D.'s plots is that the writing is so cutting, and Hugh Laurie so witty, that we can coast on insults and clever comebacks whenever the plot itself gets over the top. The general story arc of the show always remains the same ("The patient is dying! Let's give him the first obvious treatment that any doctor would consider! Oh, no, the patient is getting worse! Could Dr. House's insane theory possibly be right?"), but the dialogue makes it all worthwhile.

What does any of this have to do with lupus? Only this: lupus is a disease that causes a dizzying variety of symptoms. Since it is an autoimmune disorder, it can attack any part of the body -- skin, joints, heart, lungs, brain -- and can cause a whole spectrum of problems.

If House, M.D. took place in a normal world, then weird, ostensibly unconnected physical problems would often resolve into a diagnosis of lupus. But Dr. House seems to be aware that he is not in a normal world: in the farfetched plots of his television program, it's always something else. Always.

[Scene: the walk-in clinic. A patient who insisted on seeing a male doctor uncovers himself, revealing blood on his crotch.]
Dr. House: It's not lupus.
-- Autopsy (season 2, episode 1)