I’m 22 and I masturbate frequently and have a patch of skin that is a little darker than the rest of my penis shadow like (it is where I place my thumb when masturbating). Is this cause for concern? is it maybe just a pigment issue?
Does it itch, hurt, or change in appearance at all? If not- I don't think it's anything you need to worry about. If you see any itching, pain, or change in appearance, it's probably a good idea to have a doctor take a look.