Hello. First time posting here. Thank you in advance for any replies.  

My daughter is almost 12. She has a blue mark on her right breast, at the bottom of her areola. It started as a pinprick sized mark around 6 months ago. I've monitored it and it seemed to stay the same size. However, over the last week, its got bigger and is now slightly bigger than a pea size. 

It is tender but not hurting, she says. There doesn't seem to be a lump that I can feel and it isn't raised, just this blue spot.

I am booking an appointment with the gp but I am just wondering if anyone has experienced anything similar? What may it be? 

Thank you again for any replies. xx