[diegoperini]

Is there a testimony of someone who went through such surgery? What's the mindset of a person who really needs his/her limbs removed because of such urges?

[hnick]

One possible cause is https://en.wikipedia.org/wiki/Body_integrity_dysphoria but there are related conditions with other names.

I saw an interview years ago on TV and someone was saying it felt like that appendage was not part of their body, it belonged to someone else. It was so mentally uncomfortable they'd rather remove it.

[burnthrow]

I would never do it, but there's some convincing evidence (the experience of eunuchs) that castration evens out the male/female longevity difference.