I scratched my forearm and blood came out of very small round dots that are spread apart from each other (about 1-2 mm apart from each other). The dots themselves are very small, the size of a period mark or comma. After I scratched till it started the bleeding, the itch went away.
A few years ago, I remember I had a patch of small red dots on my arm (kind of like the surface of a basketball except smaller) and it itched but it went away or at least went dormant. Now, after I scratched my skin it reappeared and had blood coming out of it.
They look pretty symmetrical.