"When I was about 5 my sister [Kendall] and I were playing hide and seek and I hid inside this really tall, enclosed gate," Kylie explained. "After a while when my sister didn’t find me I had to climb up on this sharp pole sticking out from the gate. I slipped and the pole went into my leg. I tried pulling away to get the pole out but it just tore through my whole leg. It’s smaller now though because I grew!"
The scar can be seen in a number of Kylie's past Instagram posts, although this is one of the first in which she's specifically highlighted the massive scar.