Hello, I just discovered a 10mm dark spot on my forearms. It is pretty regular (symmetrical) and uniform in colour. It does not hurt, and there is no sign of infection. I had no bumps or injuries in that point, that I can remember. As it is pretty large, and not in hidden position, the fact that I just discovered suggests that it appeared rather quickly. Besides skin cancer (!), what else could it be? What should I look into, before rushing to the doctor? Anything I could do to self-diagnose? many thanks!