Richard Asher noted that diseases usually remain unrecognised until they have acquired a name. “A rose without a name may smell as sweet”, he said, “but it has far less chance of being smelt”. In 1877, Jean-Martin Charcot, the founder of modern neurology, described a strange disorder: patients purposely injuring themselves to gain treatment. Nothing more was written on this for 74 years. In 1951, Asher published an article describing patients with similar histories. Recalling the tall tales of Baron von Munchausen (an 18th-century German mercenary who entertained friends with stories of his imaginary exploits) Asher coined the name Munchausen syndrome. Soon after this label was accepted, articles describing similar patients began to appear. Sherwin Nuland has written “putting a name to a demon helps decrease its fearsomeness”. Medical history is filled with spurious disorders, some of which have led to iatrogenic disasters. For example, of the many theories about the role of the thymus gland in disease, a particularly fateful one was proposed in 1889 by an Austrian physician. He suggested that an enlarged thymus might be a cause of sudden unexplained death in young children. His suspicion was accepted as fact, and led to widespread action when it was established that the thymus was sensitive to radiation. Thousands of infants were irradiated to shrink the “enlarged” gland to prevent fatal “status thymicolymphaticus”. From 1924 to 1946, it was the policy of one prestigious US hospital to irradiate every infant with an “enlarged thymus”: 1131 infants were treated in this programme. In 1939, when I was a medical student in San Francisco, the city coroner proclaimed in a lecture: “Doctors who fail to screen young infants for thymic enlargement should be prosecuted for malpractice.” Years later, I was startled to hear John Caffey, Columbia University’s pioneering paediatric radiologist, rail against the thymus myth. He came to this view after reading thousands of chest radiographs. The normal thymus, he concluded, can cast a large shadow in films of healthy babies. In 1949, 60 years after its birth, the final blow to the “disorder” was delivered when it was discovered that patients given thymic radiation had an increased risk of cancer. The grip of misconceptions embodied in old terminology is hard to shake—a request for the “treatment” was made as late as 1960. As the astronomer Fred Hoyle said “Words are like harpoons . . . once they go in, they are very hard to pull out”.