I started developing some years ago dark, almost black, needle marks . The first came after about four years shooting into the same place (I had perfect iv veins). It looks like scar tissue but after continual fixing eventually becomes a bluey, then dark line. Iv got 'em on my inner elbows, wrists and a couple of other places. They begin as dots and grow into thick black lines about an inch or two long.
Does anybody else get this kinda scarring? Its a bit of a give away in summer t-shirts.