Body Integrity Identity Disorder

Otherwise mentally competent people with a strong desire to amputate their own limbs. The diagnosis did not make it into DSM-5. 

The Atlantic, December 2000

"In January of this year British newspapers began running articles about Robert Smith, a surgeon at Falkirk and District Royal Infirmary, in Scotland. Smith had amputated the legs of two patients at their request, and he was planning to carry out a third amputation when the trust that runs his hospital stopped him. These patients were not physically sick. Their legs did not need to be amputated for any medical reason. Nor were they incompetent, according to the psychiatrists who examined them. They simply wanted to have their legs cut off. In fact, both the men whose limbs Smith amputated have declared in public interviews how much happier they are, now that they have finally had their legs removed.

Healthy people seeking amputations are nowhere near as rare as one might think. In May of 1998 a seventy-nine-year-old man from New York traveled to Mexico and paid $10,000 for a black-market leg amputation; he died of gangrene in a motel. In October of 1999 a mentally competent man in Milwaukee severed his arm with a homemade guillotine, and then threatened to sever it again if surgeons reattached it. That same month a legal investigator for the California state bar, after being refused a hospital amputation, tied off her legs with tourniquets and began to pack them in ice, hoping that gangrene would set in, necessitating an amputation. She passed out and ultimately gave up. Now she says she will probably have to lie under a train, or shoot her legs off with a shotgun."