What is purpura?
Purpura is the name given to the discolouration of the skin or mucous membranes due to haemorrhage from small blood vessels.
- Petechiae are small, purpuric lesions up to 2mm across
- Ecchymoses or bruises are larger extravasations of blood.
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.
Non-thrombocytopaenic purpura – blood may leak as a result of:
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.
- Petechiae are usually present in thrombocytopaenic purpura. There may be some external bleeding and bruising.
- Coagulation defects usually present as large ecchymoses and external bleeding. Petechiae do not feature.
- Lesions of blood vessels cause persistent and localised purpura with an erythematous inflammatory component. This may be palpable. Ecchymoses and external bleeding are uncommon.
Disseminated intravascular coagulation
What is the treatment for purpura?
The underlying cause of purpura should be identified and treated accordingly.
- Book: Textbook of Dermatology. Ed Rook A, Wilkinson DS, Ebling FJB, Champion RH, Burton JL. Fourth edition. Blackwell Scientific Publications.
On DermNet NZ:
- Topical steroids
- Disseminated intravascular coagulation
- Leukaemia cutis
- Non-accidental injury
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