Ihad a cyst on the back of my head cut open to drain by doc. today i notice a lump of skin sticking out that looks like blood but its skin. what is it?

Subcutaneous tissue: Some of the tissue just under the skin. This is normal after an i;d. It will heal.

Probably dried blood: It sounds like just dried blood on the edge of the skin from the area over the drained cyst. It is of no concern but you should see your surgeon if it does not heal in over the next few weeks.

Hamangioma: This could be a hamangioma, which is a benign collection of small blood vessels that can arise in areas of trauma occasionally. However, it is difficult to diagnose this without seeing it and the safest thing to do is have your surgeon take a look. I hope that helps!