Purplish-red haemorrhages, a symptom of capillary inflammation, which destroys the blood vessels and causes multiple small haemorrhages just below the surface of the skin. They show through as purple patches, and sometimes form blisters. The commonest cause is an allergic inflammation of the blood vessels: the body reacts to the presence of a foreign substance in the blood vessels by forming antibodies. In some cases the condition is not confined to the skin, but affects internal organs and can damage the kidneys (among others). Another cause of purpura is the presence of too few platelets in the blood, possibly because too many blood platelets are being broken down in the spleen or because too few platelets are being manufactured, as in leukaemia. If the cause of purpura is treated the symptoms should disappear spontaneously, in which case no treatment is necessary for the skin condition itself.