Purpura is a condition of red or purple discolored spots on the
skin that do not
blanch on applying pressure. The spots are caused by
bleeding underneath the skin usually secondary to
vasculitis or dietary deficiency of vitamin C (
scurvy). They measure 0.3–1 cm (3–10 mm), whereas
petechiae measure less than 3 mm, and
ecchymoses greater than 1 cm.