The darker skin at the male penis is physiologically determined, the skin color of all parts of the male body is almost the same after birth, but with the growth and development of the human body and the emergence of secondary sexual characteristics, the body’s melanin will be selectively deposited, generally thicker hair areas deepen in color, especially in the male perineal area, including the penis, scrotum and around the anus, the skin in these areas are due to normal genetic levels resulting in hyperpigmentation. If the patient has no obvious discomfort or skin surface abnormalities, such as a localized melanotic nevus or abnormally increased hair on the nevus, this situation does not require special concern and is a normal physiological adjustment. If local melanin accumulates significantly within a short period of time, you should promptly go to dermatology for examination to exclude melanoma.