Unknown skin condition

AGE: 19

SEX: MALE

HEIGHT: 181cm

WEIGHT: 75Kg

RACE: Caucasian

Duration of complaint : about 2 years

Location : chest

No medications,no other issues

http://m.imgur.com/L8vNSpP

http://imgur.com/l87TUI5 this is photos,however it was smaller and during those years it got bigger and also you cant tell because of lighting in photo but this circle color is almost same as nip. I have no clue what it could be , cant find anything similar in internet, but since it got bigger I got curious what this could be