Petechiae and purpura (easy bruising)

Petechiae are tiny dots, about the size of a pinpoint, that show up on the skin or on the mucous membranes, the moist linings of the body such as the inside of the mouth. What sets them apart is that they don't go away when you press on them for a moment. Purpura is the same kind of spot that won't fade, just bigger.

A petechia is really blood that has leaked into the dermis, the layer of skin just beneath the surface. Think of a drop of ink that has seeped under a clear plastic sheet: no matter how hard you press on top, the stain stays put. One way that leak can happen is when hemostasis, the system the body uses to stop bleeding, breaks down. It can break down because there are too few platelets, the tiny fragments in the blood that help plug leaks (this is called thrombocytopenia); because the platelets that are there don't work properly; because clotting, the process that turns blood into a firm plug, fails; or because the blood vessels lose their integrity, meaning they're no longer a well-sealed tube.

In children, the cause can vary widely: a virus like dengue, a reaction to a medication, or even the pressure that builds up during a bout of coughing, vomiting, or straining.