A friend just asked me to look at a spot that's on her back where she can't see it. It looks like ordinary acne, definitely not a mole. But apparently it's a permanent feature - she's had it for years. Every few weeks, it comes to a head and bleeds, then dries up. But then it comes to a head again and repeats the process. The doctor told her it's just acne, but couldn't explain why it never heals. Has anyone ever experienced this?