Purpura is a small hemorrhage (up to about 1 cm in diameter) in the skin, mucous membrane, or serosal surface, which may be caused by various factors, including blood disorders, vascular abnormalities, and trauma. Purpuric lesions may be associated with inflammations, in which case they present a papular purpura, or the hemorrhage may not be accompanied by inflammation, in which case they are macular.
The term "purpura" comprises a group of hemorrhagic disorders characterized by the presence of purpuric lesions, ecchymoses, and a tendency to bruise easily, which may be caused by decreased platelet counts, the presence of abnormal platelets, vascular defects, or reactions to certain drugs.