A man who has had repeated bouts of depression cut off one of his own fingers, cooked it with some vegetables and ate it.
The bizarre case of "self-cannibalism" is the first known in New Zealand and one of only eight reported around the world.
South Island forensic psychiatrist Erik Monasterio and clinical psychologist Craig Prince reported it yesterday in the journal Australasian Psychiatry to alert colleagues to the rare behaviour.
Their patient, aged 28 at the time, was moderately depressed and had not consumed drugs or alcohol at the time of his extreme act in 2009.
He was assessed as having a "vulnerable personality structure".
"Mr X" would suffer episodes of low mood and sometimes think of suicide. He had been successfully treated with anti-depressant medication and received supportive psychotherapy. Once while depressed, he was assaulted by two men.
"He felt extreme anger and for the first time fantasised about not only killing his assailants, but of eating them too," the doctors' report says.
"He believed that by doing so, he would 'rob them of everything'."
It appeared his fantasies had been perpetuated by an interest in violent movies and taboo subjects.
"At the end of 2008, following another personal crisis, and while not being fully compliant with his medication, he spiralled into another episode of depression. He experienced significant insomnia and suicidal ideation, and ruminated for days about cutting off his fingers.
"In an effort to seek reprieve from these thoughts, he tied a shoelace around his [little] finger to act as a tourniquet and cut the finger off with a jigsaw.
"He then cooked it in a pan with some vegetables and ate its flesh. His plan was to amputate another two fingers the following day.
"Mr X reported initial excitement - non-sexual - and a sense of relief from his ruminations. Given the instantaneous benefit, he felt that there was no point in cutting off any more fingers."
The man later regretted the act of self-harm - his first - "because of its debilitating effect".
The authors say Mr X had difficulty regulating his emotions during personal crises. His violent thoughts provided relief from intense emotional distress and a sense of control.
"It may be that the act of cutting off his finger - and eating its flesh - made staff take him more seriously and provide the care and understanding he longed for."