Why are some teens getting into self mutilation?

Personality: There are problems ranging from body image to borderline personalities who only feel something when the do this this can be a seious sign of illness.

It is filling a need: Someone who feels empty inside may cut to feel "something". Someone who is hurting emotionally may cut so that the physical pain will distract them. Some cut to punish themselves. One may cut in the belief that they will let out negativity or evil.