The male coronal groove of a circle of purple is not normal, is likely to be the foreskin glans, or the foreskin is too long to cause. 1. glans penis: because glans penis will cause inflammation in the coronal groove, resulting in local bacterial infection, this situation usually leads to a circle of coronal groove appears purple. 2. circumcision: because the foreskin is too long, the penis can not be fully extended during sexual intercourse, at the end of the sexual life of the penis will be stuck in the foreskin mouth, if not reset in time, it is likely to lead to penile bruising, resulting in the phenomenon of purple. A circle at the male coronal groove is purple, and when the symptoms continue not to improve, you should immediately go to the hospital for examination, and use medication under the guidance of the doctor, and do not use medicines indiscriminately.