DermNet NZ

Facts about the skin from DermNet New Zealand Trust. Topic index: A B C D E F G H I J K L M N O P Q R S T U V W X Y Z


What is purpura?

Purpura is the name given to the discolouration of the skin or mucous membranes due to haemorrhage from small blood vessels.

Extravasated blood usually breaks down and changes colour over a few weeks from purple, orange, brown and even blue and green.

Classification of purpura

There are many different types of purpura and their classification in medical literature, depending on the appearance or cause of the condition. Often there is overlap and difficulty in classifying any individual case of purpura. The following table is one way of classifying purpura according to the underlying cause.

Platelet disorders Thrombocytopaenic purpura
  • Primary (idiopathic) thrombocytopaenic purpura – destruction of platelets due to unknown cause
  • Secondary thrombocytopaenic purpura – caused by external or internal factors, e.g. drugs, infections, certain diseases
Vascular disorders Non-thrombocytopaenic purpura – blood may leak as a result of:
  • Damage to small blood vessels
  • Increase in the intraluminar pressure
  • Deficient vascular support, as in aged or sun damaged skin (senile purpura)
Coagulation disorders
  • Disseminated intravascular coagulation – clinical picture varies from a severe and rapidly fatal disorder (purpura fulminans) to a relatively minor disorder
  • Heparin induced thrombocytopaenia – purpura and necrosis due to anti-platelet antibodies inducing platelet plugs that block blood vessels
  • Warfarin induced necrosis – purpura and necrosis due to blood clots related to relative protein C deficiency early in treatment

What are the signs and symptoms of purpura?

The signs and symptoms of purpura vary depending on the type of purpura. The following broad generalisations may be made.

Suction bruise
Venous stasis
Steroid purpura
Disseminated intravascular coagulation

What is the treatment for purpura?

The underlying cause of purpura should be identified and treated accordingly.

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Author: Vanessa Ngan, staff writer

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