Suggest Treatment For Purple Raised Dots On Penis

Hello, I'm forty-two, I have right next to the opening of my penis little purple raised dots that have been there for a long time as long I was little and they don't hurt or itch. I was just wondering what they are called? I did see a doctor and it's not an infection or any std, He did tell me but this was a long time back and I just like to ask of your answer on this. Thanks