"Bruises on the legs and arms are very common," says Fisher, "and if the bleeding is significant enough, a large collection of blood can form - which is referred to as a hematoma." If you'd like ...

Henoch-Schonlein purpura (HSP) produces a distinctive rash on a child's arms, legs, and buttocks that looks like bruises (purpura). It is a type of vasculitis, or inflammation of blood vessels.