Believe it or not, what you see in this photo is not a result of some kind of workplace accident, this is a result of an intentional thumb amputation by a fan of extreme body modifications. You can even see the tools he used for self amputation in the photo’s background.
I do not know whether the man had his thumb re-attached afterwards or whether he just kept the severed part as a souvenir, allowing the hand to heal with part of it missing. I also wonder if he used any local anaesthetic to cut his own finger off. Either way, it is a very smooth cut for a do it yourself amputation.