Hemangioma

Hemangioma – Benign tumor, usually in the shape of a ball, but sometimes a flatter mat, formed by a collection of excess blood vessels in an area. Because blood vessel cells are usually transparent in thin smooth muscle cells, hemangiomas are usually the color of the blood that runs through them. If the blood has a lot of oxygen, or is more arterial, the color is usually bright red. If the color is dark, the blood is usually low in oxygen, venous or possibly stagnated.

From skincancerinfo.com.