What Causes Brown Mole Like Spot On Penis?

hi i have a small brown mole like spot on my penis and i am quite worried, i dont remember when it suddenly appeared but its been there a while now, i want some more information on what it could be before i go to the doctors to get it looked at, could you help me? its small and light brown like a mole but it blends in likes its under the skin abit, it is not raised at all though