Looks like necrosis. Maybe frostbite or trenchfoot. reminds of a horrible video of some drunk russian vagrant in the park with his foot completely atrophied to the bone. What a nightmare.
I think this was posted before and I think it was written that this dude is on "god journey"... Religion shit. So yeah, I assume he cut it off himself.
It's some sort of religious thing. I've seen this picture on here in a thread about how some people take religious fervour and suffering to insane levels.