V. S. Ramachandran at Edge.org:
One of the peculiar syndromes, which we have studied recently, is called apotemnophilia. It's in fact so uncommon that many neurologists and many psychiatrists have not heard of it. It's in a sense a converse of phantom limbs. In a phantom limb patient an arm is amputated but the patient continues to vividly feel the presence of that arm. We call it a phantom limb. In apotemnophilia you are dealing with a perfectly healthy, normal individual, not mentally disturbed in any way, not psychotic, not emotionally disturbed, often holding a job, and has a family.
We saw a patient recently who was a prominent dean of an engineering school and soon after he retired he came out and said he wants his left arm amputated above the elbow. Here's a perfectly normal guy who has been living a normal life in society interacting with people. He's never told anybody that he harbored this secret desire—intense desire—to have his arm amputated ever since early childhood, and he never came out and told people about it for fear that they might think he was crazy. He came to see us recently and we tried to figure out what was going on in his brain. And by the way, this disorder is not rare. There are websites devoted to it. About one-third of them go on to actually get it amputated. Not in this country because it's not legal, but they go to Mexico or somewhere else and get it amputated.
So here is something staring you in the face, an extraordinary syndrome, utterly mysterious, where a person wants his normal limb removed. Why does this happen? There are all kinds of crazy theories about it including Freudian theories. One theory asserts, for example, that it's an attention seeking behavior. This chap wants attention so he asks you to remove his arm. It doesn't make any sense. Why does he not want his nose removed or ear removed or something less drastic? Why an arm? It seems a little bit too drastic for seeking attention.