Symptoms. Tiny red, brown or purple spots, about the size of a pin-prick, that appear under the skin are petechiae (also called purpura). These spots are flat and don’t itch or blanch (turn pale) when you press gently on them. A child may have just a few spots or clusters of them, often appearing on the face, chest, stomach or feet. Causes. Petechiae are caused when tiny blood vessels burst underneath the skin. Kids can develop them after a bout of coughing or vomiting, usually on the face. But widespread petechiae can be associated with serious disorders as well.