bump on outer labia

Hello!
I was wondering if someone knows what could this bump be? http://postimg.org/image/z2kt9lejh/
I've had it for over a year, it's located on my outer labia. It's been slowly growing and is now approximately 0,5 - 0,7 cm big. It doesn't hurt. It feels like a continuation of skin.

Thank in advance for answering.