Seven unsolved medical mysteries - New Scientist

"In this week's issue of New Scientist [the author] edited a profile of a doctor who is the real-life version of TV's House MD. William Gahl recently set up the Undiagnosed Diseases Program to hunt for the answer to mysterious diseases that have defied all other medical experts (read the interview at New Scientist). "This got [him] thinking about ailments that have perplexed the medical profession. Here is a selection of the most unusual."