What does a hemo dialysis site look like on your arm?

Lump on skin: Hemodialysis sites look like engorged veins. If they are "fistulas" (artery connected to a vein) the lump on the skin follows the natural pathway of the vein. Over time these can dilate and become aneurysmal. The arterio-venous grafts are basically synthetic / plastic tubes which are placed right under the skin. These you can see and feel. The actual needle puncture sites develop small scabs.

Buldging vein: It could look like just prominent vein to a bigger vein.