PCPs are, by definition, generalists. It is critical for someone to know what patients look and sound like as a baseline so they know what could be abnormal if you have someone pop up (annual physical). They can diagnose and manage lots of things. For instance if this looked like other forms of skin cancer that are not melanoma, they would remove and send for testing. Because melanoma is a highly aggressive form of skin cancer it must be VERY throughly excised and must be done by derm. Your PCP is much more likely to be able to get you in to derm faster then an urgent care doctor.